If you don't like dialogue, I recommend staying away from RPGs in general. If you think you like dialogue but you don't like Witcher 3, you probably don't like dialogue (it's one of the better-written PC games in recent memory). W1/2 don't really have less I don't think. W1 probably had less but had gameplay issues. W2 honestly was a slog of conversation with the occasional fight, though I may be in a minority on that one.
These games are story-driven, so yes there is lots of dialogue throughout. If you don't like making decisions based on dialogue paths, then this probably isn't for you.
Witcher 1 is also...a bit dated and always had pretty terrible combat mechanics. You may not like it so much. Witcher 2 is quite a bit better, but is also heavily-railed (like a CoD-type game). Dialogue is much more involved in that one than the other two.
No, I think you're very accurate here. W2 was mostly designed around the dialogue, as much of it was running back and forth to gain information about what to get and how to fight the main big monster of the area. All between that, a substantial peppering of what I call nonsense political bollocks in a fantasy setting. It gets pretty ruthless in the late game, and I found my eyes rolling for most of those sequences...I just didn't care anymore at some point.
I guess for me, what differentiates Witcher 2 from being one of the more forgettable/frustrating games of the time period and Witcher 3 one of, if not the best of the same era, both being dialoguey and political, is that on top of being on rails, Witcher 2 is heavily plot-driven. All the eyes-glazing nonsense and detail is really just meaningless. Witcher 3 is heavily character-driven. The expanded side-quests are incredibly well-done.
RPG's as a whole (with the exception of some Action RPGs) have lots of dialog. Be it the Witcher Series, Dragon Age, Mass Effect, Pillars of Eternity, etc etc. If you don't like dialog, avoid these games. They cater to people that like an expansive story and character development.
Witcher 1's combat is certainly different. When I went back to replay it earlier this year, it took some getting used to. But once I did, it flowed pretty nicely. But then I started Witcher 2 immediately after it and found myself trying to play it like Witcher 1, which did NOT work. Also, Witcher 1 is almost twice as long as Witcher 2. And Witcher 3 is four times as long as Witcher 2.
I didn't think i would like it. But I like games with a good story. Once I started playing I couldn't stop. I've yet to reinstall it and finish the game. I'm playing greedfall right now and I think that game feels like it has more dialogue.