Well obviously you buy your setup based on what applications or games you use. HW-E makes sense for some people, but by and large I think it makes the most sense for what someone does outside of gaming. But if someone plays tons of BF4 MP, have fun with it.
That said the typical usage scenario is someone who plays a ton of PC games. Not just the same one. For such an individual on a budget, the fact of the matter is HEDT usually costs 500$ more than the mainstream platform - and adding insult to injury, since the mainsteam platform usually has better IPC - it can even beat the HEDT platform in quite a lot of games. Case in point being the IVB-E vs HW. HW wins some games based on IPC grunt. It isn't a significant difference in performance obviously, but this all goes back to someone with a budget and someone who plays a wide variety of PC games. For someone like that, does HEDT make sense? Hell no, no it doesn't.
But certainly everyone should buy based on the games and apps THEY use. If there's a killer app that someone plays or uses which would benefit from an 8 core, buy accordingly. There's nothing wrong with that, that's great. I'm just saying that games or apps like that are outliers at this point and time and the wide variety of games benefit more from IPC. Which wouldn't make much of a case for HEDT. But if budget isn't a consideration then the HW-E will certainly be a beastly setup. No doubt about it.
In the end, to re-iterate, the buyer should buy based on what apps / games matter most to them. Right now with PC gaming, IPC is king - but If there are a few games which would be better on HW-E and budget doesn't matter, go for it, that's awesome. Absolutely nothing wrong with that.