^I've heard that and I've never really understood the compulsion.
I don't understand it either, but that's partly because if I was to roleplay myself into Mass Effect, I'd be too lazy/scared to go on any of the missions. But my brother says that he played through the game twice, and both times he played as himself, which means that he probably made the same decisions.
When I created my first character, I intentionally made him black because I wanted him to look nothing like me, then I hit onto the idea of making him look a bit like Sisko. Then I named him Benedict, because I thought that would be mildly humorous. The second time I played through, I made a female character intended to be completely unlike Benedict, that way I could make the opposite decisions to see how they played out.