Goku is the most highly requested non video game character for smash, and he's more requested than a lot of other video game characters [some who're in the game, like Bayonetta]. Look around pretty much any smash brothers message board and you'll find topics about Goku. People saying they want him in the game. It's pretty clear there is a rather large following of people who want this character in the game.

 His gaming history and influence on various characters [who're in smash] and gaming tropes that are very much inspired by the Dragon Ball series [mostly Z ]. Ryu, Sonic the hedgehog [Super Sonic is inspired by what again....?], etc..

To sum it up, people want him in the game, licensing issues aren't an issue, he's a very inspirational character in the world of video games, he's got a lot of video games.

If he makes it in, I'd be pretty excited. If not, I'm not exactly disappointed... but whatever.