Personally, while I've been deeply attracted to people much older than me on several occasions, I find that the generation gap can and does get in the way. We just... have different interests and such, and it's harder to relate than with someone closer to my own age. And a relationship has to work as just a relationship before it can work as D/s, at least for me. So that's why I hope for a younger dom. (Though I don't let it stop me when I do get interested in someone older. It'd be foolish to turn down what might be something really good just because the age isn't right, I think.)