Yea, WF/TF was one of the worst things they've ever done to the game. My opinion, just like yours is that you think it's good. Guess it's the raiding purist in me. Elitist, sure, but you should never, ever, be able to get high-end items from killing random mobs or completing a simple quest.
Everything every game developer does is to keep people playing, so I'm unsure how that cynical or something? I didn't think that would be the part you would get hung up on. It is true though that the more someone plays, the more likely they are to buy something from a shop.
The last part... is tricky. Back when there used to be one raid size per raid there was nothing to do when you cleared the raid except wait for the lockout or farm for mats (I always bought from the AH heh). Then came 10/25. That was nice, and you basically ran the opposite size with a PUG. As a raiding purist, I enjoyed this setup. Then came 10/25 N/H. As a raiding purist, *and* as someone who still had gobs of time to play games, I enjoyed this too. Then. Raiding was turned into an abomination with Dragon Soul. While I quit the day it was released, I've come back multiple times since, and always still troll MMO-C but Dragon Soul (see: LFR) was when I started seeing players complain about "difficulties". I never once seen anyone complain about difficulties vs more raids as much since that drastic change to raiding happened. Sure, you always had people who had nothing to do once they cleared a raid for the week and wanted more raiding (I was the same way), but that to me was a good thing. That was players literally loving the game/raiding so much they wanted more. As funny as it is, people who complain about trying a higher difficulty use that excuse because... they can't do higher difficulties. Coupled with the fact that they *are* fundamentally correct. Higher difficulties isn't "more content", so it's also the same thing as always. They love the game (well duh, they are doing easy difficulties) and want more raids. Wanting more raids after you cleared a raid has never gone away.