Because he's not important. As you said, they were scrambling for any characters they could use. I don't want him gone, but he should be first in line for the cut.
Are you kidding? Falco is important to the series. Don't get me wrong, Wolf should have had Falco's Melee spot, but Falco is still important. He has the most backstory in the StarFox series, excluding Fox.
Bolded is unimportant. Shiek is a different character, and is counted as such. You're saying Shiek should stay because she's popular. I'm saying Lucario should stay because he's popular, and Ike should stay because he's popular. Plus, Ike is another FE rep.
Shiek and Zelda should remain as one character. That's how they were in OoT -- one person. Sacrificing an extra Zelda rep for the sake of a Down-B move is ridiculous.
Ike should stay. Lucario... hrm... honestly, I would like to see a second Pokemon Trainer that reps the third, fourth, and fifth gens rather than Lucario.
But, Lucario does have a lot of popularity, so there's a chance he'll stay.
I was using the characters as examples. Lucario and Ike are very unique, yet plenty of people want them gone.
It's because people prefer other characters from the series. I know that I want to see an FE mage in, but not another sword user. And hopefully I'll get that because Smash caters more to it's Japanese fanbase, where FE has huge popularity.
But, I still think Lucario might be cut. Do I like how he plays in Smash? Yeah, I play him a lot. Do I think he's one of the few tolerable fourth gen pokemon? Yeah, he's pretty cool. Do I think he should have a spot over Mewtwo? Definitely not.