Just so I can kill this argument...
Before smash bros. was what it is today, it was a fighting game called Dragon King that Sakurai developed :
http://www.ssbwiki.com/Dragon_King:_The_Fighting_Game
It features a bunch of fighters with styles inspired by Kamen Rider, or it's equivalent, Power Rangers. Captain Falcon is indeed the Dragon King, and a lot of his moves come from the game, if not all of them.
It worked for Captain Falcon for the same reason it worked for characters like Fox and arguably Yoshi who is in many ways a vehicle himself: They had a nich. Falcon was a bounty hunter in a flashy costume, Fox is a mercenary with high tech equipment, and Yoshi could just kick the **** out of you with his Tims. Even though most of it was made up it was true to character.
So what can't it work for someone like Andy, Sami, Eagle or whoever ? Well it can, but it's not likely. It would be very hard to implement moves that are made up that stay true to the gimmick of the game. I mean they did do it for Marth, but he already fought so it's a no brainer, but making a commanding officer work while implementing mechanics that are interesting (not just send out tanks) would be hard and may look awkward since the characters are wielding real weapons, which Sakurai for some reason does not want to support. Not to mention that advance wars is just one of thoseniche games that was amazing but was outshined by Fire Emblem. F-Zero, Star Fox and the like were major contenders from home consoles and really big during their time.
I love Advance Wars; hell I still play Dual Strike. Do I expect a character from the games to be playable ? No, not really, so I just move on. In the end I just learn to love whoever they put in smash. I never played Animal Crossing or Wii Fit, but I'm loving the characters so far; they grow on you.