Gen III sux, and everyone knows it. Gamefreak really had a return to form when they made Gen IV though. Gen IV is the best gen hands down, no argument.
Anyway, I think it's interesting that the Gen I Pokemon can only go to the new gen. One of the things that prevented inter-generational trading was Pokemon having HMs. I'm wonder if that's related? There's no move deleter in Gen I, so they probably had to do a fix for Pokemon Bank. But are they doing something different with HMs in the new games?