It usually depends on how much I like the game, how good I am at games of that type, and how willing I am to learn. For mooost games, however, I play on normal. For shooters, I might boost it up to hard. I completed ME2 on the hardest difficulty, although that really just made the game longer rather than harder (giggity).
So yeah, normal for me. I'm trying to think of any games that I play on easy.... I played halfway through Fire Emblem Awakening on the casual setting, although then found it boring. That's all I can remember. It took me a while to work up to Prince difficulty on Civ V, although I now win those almost 100% of the time. IF I played RTS's I'd probably stick those on easy, because boy, I suck more than [insert personal mother figure here].
But yeah, I totally understand why people would want an easy mode. For some, an easy mode would still be a challenge. I know my sister would struggle through Dragon Age: Origins on easy. She just doesn't have the years of experience with hotbars, party tactics and all that. And for others, they may want to roleplay as someone who is super powerful, or they may just want to see the story. I can dig that. That's not meant to be condescending either, go for it.