"Deserve" isn't really a word we need to use.
I'd argue Dark Pit doesn't "deserve" to be in, but he is, and he has fans. I'd even argue Cloud doesn't "deserve" to be in a game dedicated to Nintendo's history, but he's also in and I assume the majority of the fanbase disagrees with me.
There's no clear outline of rules for who's in and who's out. It just comes down to who was available, who Sakurai liked, and what the time/budget constraints were at the time. If Sakurai wants Goku in and the various companies that own his rights want him in, what's stopping them from putting him in after Clou'ds inclusion? The fact that he doesn't deserve it?