why does sakurai like to do that
Here are my guesses, not some are copy and pasted from a post I just made:
1. He is Ness' successor. Normally, one would assume he would have all of Ness' moves. However, from the looks of it, Lucas may be half Ness and half new stuff. This explains PK Freeze and Starstorm being used by him.
2. His lack of PK Love is due to Claus using it. Presumably, no character will have the same final smash.
3. None of Lucas' PSI could really be used in Brawl aside from Flash and Love. Although, it's not like him using items from the game is that absurd.
As for Kumatora and such, we don't know yet for sure if they're out just yet. For all we know, Duster and Claus are in and Kumatora is Lucas' Falco.