I'll say after messing around with Pikachu in the demo, I'm with you on the rage system likely being beneficial for Marth and Lucina. While I can only assume they put it in the game as a sort of catch-up mechanic, it feels like it can be the total opposite of that with some characters. Just considering their great mobility and how being able to safely apply pressure on a lot of the cast...yeah. Scary.
Lucina should especially benefit. Her non-tipper property will/should allow her to deal with pressure better, as well as having a little more favorable of a time in potential rushdown situations.
I know the use of Pikachu doesn't make sense for the rest of that, but hear me out. I've noted that whenever I get to high percent as Pikachu and I manage to take my opponent's stock, the game just snowballs most of the time. I keep applying pressure with his fairly sick mix-up game, and it puts them in a place where all their kill moves are unlikely to ever land and everything else they do, due to Pikachu's great mobility, is probably just resetting the situation. It was stuff I noticed that would also apply to our favorite swords(wo)man, so I figured I'd share my thoughts.