I have the same issue with Skyrim, I mean, I like the game, but I cannot be bothered playing it more than 30 min at the time, which is weird by my own standards, I do not think it has anything to so with getting older as some people mentioned here before, it only means that YOU do not find it interesting, even if your brain do not understand why.
I still get super excited from playing games I really love, and if I don't have that spark, it simply means that "I believe" I like the game, but deep down, I am just lying to myself.
That said, I was not among the hyper crowd when I got this game, so I played it with no expectation, and created a trooper (First character), and hated the bland, boring , generic starting area, to the point, I was about to loose interest in the game. Luckily however, I tried Consular after that, and absolutely changed my view on the game, the world was beautiful, the story made sense and it didn't make me sound like a *** everytime I gave an answer to my storyline.