Depends.
When I 'get' the game and like it, I find the challenge to be usually worth making an effort.
If the game sucks, I either stop playing it, sell it or try and return it. If I just feel like finishing a sucky game, the option to dumb things down could come in handy. But that's really only for shitty games, crap implementations, lame battles and other inferiour experiences.
I get quite angry when a 'good' game suddenly asks me if I want to lower the bar after, what, dying twice in a row to whatever random glitch or bug. Plain doesn't work for me.