"No more vets" would be entirely arbitrary and suite no real purpose. Wolf is more popular than 90% of New Comer suggestions for less work, and is even more relevant than most ballot characters.
If Lucas was the "cut Brawl vet" what does that make Mewtwo and Roy? Both cut Melee vets? Or are they allowed to have unique marketing tag lines, while Lucas and Wolf don't for some reason and have to use the same one? Despite no character in the game filling Wolf's niche of being a feral, savage humanoid that fights with teeth and claws. Charizard and Bowser are the closest, but they're monster characters.
Perhaps they find out Ryu is by far the best selling DLC character and decide it's more worth it to pour everyone's efforts into making three newcomers instead of two for more bang for their buck.
That would be strange information to pull out of Ryu's sales.
Mewtwo - Was released for free to a huge amount of people, many of which ended up just giving their codes away on the console they never play
Lucas - Wasn't really even that popular of a character in Brawl. Japan only release. Semi-clone
Roy - Only mildly popular from Melee. Japan only release. Semi-clone.
Two semi-clones and a character given out for free. Of course Ryu would sell more. Plus he comes with a stage. Had Mewtwo came with a stage and not been given out for free, I imagine his sales would be not that far off from Ryu and he was a heck of a lot more work to implement than Wolf would be.