I usually play Bethesda games in two passes.
First pass, I complete about half the game (excluding the main storyline, because you never play the main storylines in Bethesda games), trivialize the badly balanced mechanics, max out on purchasing ability and gear and quit.
The second pass, I do the same thing, except I dump in a ton of mods and usually play something other than my preferred stealthy type. Whether by chance or by rote, I generally do most of the same things I did before. Then I uninstall it and pretty much never look back.
I swore I wouldn't buy Skyrim at release, but I got sucked in to the hype and the commercials. I enjoyed it pretty well for about 20 hours, enjoying the things Bethesda had improved on (their vistas, somewhat more diverse dungeon designs, better side areas.) But then all the things I didn't enjoy about the game, plus all of Bethesda's classic short comings, really started to eat away at my fun. There's that wall you eventually hit with your character, and the prospect of a couple unique items and the many generic filler quests just isn't enough to keep me playing.
I plan on doing phase 2 of Skyrim, at some point. But between FO:NV and Skyrim, I have about a whole game's worth of Bethesda content I've never played, and I just don't feel like adding to that pile anymore. (To me NV was, despite Obsidian, still thoroughly imprinted by Bethesda's content and design philosophy.)
I feel like I've been playing the same game, over and over and over again, since Oblivion and this time I'm waiting on you people to tell me whether the cycle is going to repeat itself. Because if it is, there's other games I can be playing instead.