I'm too busy to devote that much time to a game anymore and some things (like maxed out levels) are just not fun to do or add anything to the game.

I do keep certain aspects of completionism for replays of old games though, I still want to play the original FFIV and do a run-through where I get every item in the game including the adamant armor cause I have never done it, but like hell I'm going to get a complete set for my final party, smurf that trout.

If the game is simple enough or I discover halfway through that I am not far from actually doing a perfect game, I have no issue going for it. I do like some player challenges but I never do them very often mainly cause I have a hard enough time justifying replaying a game when I have a backlog to get to.