I buy most games that come out that I think I want to play at some point. Thus, I have a large stack of games (and books) that I haven't even started yet. And no, I'm not a casual gamer. Video games are my main hobby.
In a way, I agree that some games are too long. When I buy a heavily story-based game, I don't want to play through filler that was added to artificially extend the total playtime. I want to play through it, have the intended experience, and move on.
Now, if those games have replayability for those with more time than money, fine. Look at most older games that weren't RPGs. You could finish them in an hour or two, but they were fun enough that you'd want to play them over and over. I think there's still something to that.
When I was a kid and I had more time than money, longer games were good because I couldn't afford many games. Now, I have the opposite problem.
For what it's worth, I do also play games that aren't story-based that you never "finish"--fighting games and the like.