Probably Konami giving the middle-finger to almost anything and anyone for whatever reason.

There were 5 if I recall correctly. Azrael, Blade, Blue, Robo-Ninja and Spikeman.
There was also Sasuke, Renji and Vegeta that were going to be added alongside Rock Lee, but have since been deconfirmed.

The point is, those guys were considered good choices when X was taken out of the bunch. Now that roster got revamped like in 2011, it's (probable?) that he could have been added in.
Also, if any of the younger links make it to the game, there'd no excuse for X not being likely. (Keyword: likely, that doesn't mean he's in or out)

Also, to elaborate on Kirb-Star's post, anybody that was cut, save for the characters who were intended in being in, could make it in. Anyone like InuYasha, Mega Man X, Mr. Incredible, & Young Link have the possibility of returning, especially Young Link, as long as they made at least one appearance on a Nintendo console.

Mr Incredible was already cut in the April Fools video don't you get it

Why have Young Link? If they are gonna add Young Link, they should at least make a custom moveset for him. I mean, whats the point of adding a smaller version of a character if you can just add Toon Link whos somewhat different?

The Majora's Mask moveset would be perfect for him.

^Yes please, I've always wanted that.

And regarding X, as long as he has a completely different moveset from classic Megaman, I wouldn't mind his or Zero's inclusion either.

I'd rather not have Young/Toon Link at all than have them with a changed moveset. Same with Ganondorf; if he's not still a Captain Falcon clone, then I don't want him.

I still don't get why Ganondorf is a Captain Falcon clone, I mean, he uses his sword in most Zelda games? You can say ''oh too many sword fighters'' or whatever, but I'il take a swordfighter over a clone.

I wish Ice Climbers And The Duck Hunt Duo will join SSF2 Beta...

#IceClimbersForSSF2Beta
#DuckHuntDuoForSSF2Beta

He only just barely got in Melee. The development deadline was fast approaching, and Captain Falcon was the only existing character with a similar body type.

I don't mind him being a clone, though, because if you ask me, he's one of the most hard-hitting and just plain satisfying characters in the series. Make him closer to his canon self, and he loses that, becoming really generic-feeling. You know, like he does in Project M.

I think he still feels really fun in Project M, with the exception of side b in air, which I've always found pretty boring actually.

Ice climbers would be nice to have, as long as wobbling isn't broken.. The thing about Duck Hunt is that he'il be popular for a few weeks/months, then he'il die.

Wobbling Technique is the reason why i always use Ice Climbers in Melee. Duck Hunt's popularity will die? Is that what you mean?