Milee, you're so right! If you don't try other genres, you never know if you are missing something you may love. And hey, why not revert to childhood if we didn't get to play these fun games back then? WHEEEEEEE. I really thinks these games keep our minds active and imagination going, so that we aren't older than we have to be.
Nipomo, another thing about RPGs that is immensely attractive to me, is that most of them are so less structured than most adventures. You can go where you want to, and decide how you want to accomplish your goals. As the others have said, you invest more of yourself in your character, and because of that, the game seems more immersive. Also, most RPGs take longer to complete, so you work with/as that character, or characters, for quite some time - I played Divine Divinity for months, and I think I could play Morrowind for years without running out of things to do.