This is an interesting subject. I think that there's a few aspects directly and indirectly connected to this (to the subject of PC gaming seemingly suffering from the lack of specific game genres).
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Maybe more action-adventure platforming-oriented puzzles-and-dungeons-filled games in the veins of The Legend of Zelda, Banjo-Kazooie, Conker's Bad Fur Day or even Shadow Man (which itself is already on PC). If not, maybe more Star Fox-style sci-fi aviation-themed "corridor shooter" games (branching on multiple paths prior to missions, with a crew of different pilots to select or order, etc).
The problem with this is that whatever one could suggest you'll inevitably be replied at some point that you might as well just buy such games on consoles (be it this generation or from previous generations). After all, those game styles that seem to be lacking in numbers on the PC platform are indeed found on the seemingly infinite consoles games library (and by that I am referring to all generations of consoles, not just the current one). I mean I gave the examples I know best myself, since of course I played those specifically on consoles when I was younger, and never really played games "like those" on the PC (well I did, but there's only a few here and there, which I guess is the point indeed). So, sure I would like to see a Zelda-style action-adventure of epic proportions and exploration, story-driven and light-hearted (no need for extremes of violence, which is why I compare it to the Zelda franchise) on the PC but then again I might as well just fire up Skyward Sword on my Wii (which I do own).
Also, I would add fighting games, but unique to the PC platform (yes, better played with a good controller obviously). I would love to play the Mortal Kombat reboot but they ignored the PC platform (fortunately Street Fighter IV is good enough). However I haven't seen a big budget style AAA dev team-made "PC exclusive fighting game" in... ermmm... forever? Anyone can think of any PC platform-unique fighting game made in recent years or even ever made at all? And I do mean exclusive to PC, one that has never been released (or at least never made for) for Arcades or consoles. That was the "job" of Arcades back then. It also worked very well on consoles for obvious reasons (the audience, the controls and easy to let multiple players play together). It wouldn't have worked well back then on PCs I guess... but what about today? Internet connections are significantly faster so online fighting games would work (Street Fighter IV works well, at least for me anyway) and USB controllers are literally identical to console controllers so no issues there.
There's a bunch of game genre and styles that the PC platform could benefit from, it'd add variety which I think is not lacking on the PC especially, especially not since the Indie dev scene seems to be growing since the past four or five years or so (and Indie devs aren't afraid to try fresh types of games or simply go old-school style but with added 3D effects in background, etc, similarly to Trine for example). But I think that what I'd like to see is a bigger company trying something different. Let's say... a company such a Valve, Blizzard or BioWare trying something like RTS (Valve, not Blizzard) or something like Zelda or Shadow Man from Blizzard or another company like... say... BioWare or Bethesda trying something like a FPSMMO or maybe just... you know... just something different from what they're "used to do", or what is "expected" from them (by both the gamers and themselves internally).
What I don't like hearing is when people claim something like "Blizzard should stick at making RTS games", or "Valve should stick with FPS games forever because they're good at it". Look at id Software, should they stick with FPS gaming? I don't think so. Sure, I can't wait to see what's in store for DOOM 4... but frankly RAGE isn't exactly the type of game I "expected" from id Software... and that in itself is a problem. Just the fact that I expected any specific type of game from any developer, is a problem (in my opinion). If id Software wants to explore another genre and go space-based flight simulator mode on their audience, then sure it would cause some sort of uproar amongst "their fans", but who knows, it might work better than DOOM 4 would or better than RAGE.
The same I think can be said with BioWare, ever since ME2 they have obviously changed their priorities and many game-play mechanics seem to reflect new ideas (new ideas within BioWare, I mean, not within the whole gaming industry). From ME2 to DAII and ME3 (and possibly DA3, too) it's almost as if they tried to twist those enough to make them more action-oriented but obviously they couldn't do that "too much" due to the very games they were working on. But then I feel that they might want to do something else entirely... it's like I feel that they're getting "tired" of making epic story-driven series (literally I felt it within their latest games, namely DAII and ME3) and they might want to try something completely different... well then do it? Seriously guys give it a go! Give it a try and maybe it's going to work, the problem is if you don't try you'll never know.
This is an interesting subject overall since I believe there's many reasons, some of which shouldn't exist, that explains why the PC platform seems to be lacking in specific game genre and styles when in reality it really shouldn't be lacking anything. The PC platform has everything going for it to accommodate all gaming has to offer, be it hardware, software or peripherals, it's no worse than consoles.
There's of course some things that consoles - still to this day - do "better" (is however occasional, or situational more than anything) than PC gaming is the obvious easier proximity when comes the time to play with friends at home (or their place), when you can bring your own console and two or three extra controllers and already you're ready to have fun with your friends, drink that cold beer and eating the pizza. The "atmosphere" and social experience that gaming together with consoles can bring is something that in my opinion PC gaming has never been able to approach. The one and only exception for PC gaming is the obvious LAN method, but it has never been very practical ,or efficient. When you have to connect multiple gaming rigs together in the same room with all that wiring in between tables and whatnot (not to mention to combined sounds from fans and heat emitted from said room with all that hardware working in there and the people in that same room... it adds up you know... ugh).
With PCs if you want to play "with others", it's usually either on-line (while you're still physically alone in your room, that is) or... nothing. With consoles it's either online or you can invite a friend or two home and play games on the same screen and have fun talking and just... you know, having plain ol' gaming fun home on the counch with friends just like the good ol' days when we brought our SNES, Mega Drives and PSXs to our friends place to show them our newly bought games and play them together.
That's one part. The other part is of course the fact that consoles hardware is the same for everyone, and developers making games exclusively for consoles don't have to worry about different hardware and/or software configurations and setup and whatnot, they know it's for the PS3, 360 or Wii and they go from there but that's it. They don't have to test this and that on a 1GB DX9-only card and then test it on a 2GB DX11-capable card, nor do they have to "add" a DX11 mode nor do they have to make different GUIs for a console-to-PC port. And so many other things... it's obviously easier, most likely less expensive and probably more efficient to just "stick with consoles" and let go your imagination on those platforms, while the PC platform usually needs to be content with only ports and the occasional (albeit rarely "fresh") exclusive, which happen to be "just another shooter anyway" that you might as well just go buy on consoles to start with.
Well... anyway that's my views on this, I typed this much since I feel that there's certainly more to this subject than just developers "forgetting" about making this or that game genre for the PC platform, it goes far above and beyond merely shrugging off a space simulator. It's related to trends, popularity, expectations, on-market large-scale targeted audience efficiency (business, or in other words "go fish where the fish bite"), and... of course money.