@Zzuxon
Again, what Sakurai decides on is what he deems as right. It doesn't always matter what we want. Considering he is the one who is choosing the character, it should be assumed until it is seen as different that Sakurai found somebody who he felt should get in over Toad.
And there really is nothing we can do about it, so there isn't any reason to get too upset.
Basically.
Maybe it could be due more "accurate" character presentation (Toad is Peach's servant and fits humorously as her meatshield due being a spore-spewing shroom and a "bodyguard").
Maybe the view/opinion that Toad/Ridley don't fit as a fighter (Other only helps Mario and is generally cowardly to help Peach full-on like the Mario Bros do. Another is just too---- wait for it- intimidating and badass boss to be downscaled as a playable, which could take away it's appeal)
The resources to reserve on characters the team is more willing to work with enthutiasm. And last but most likely that Toad (and/or Ridley) isn't viewed as a worthy of a fighter over someone who could make make Smash Bros feel "unique" and "full of surprises" instead of just "full of expectations." moreso than Toad.
Remember, due this all above we got Wii Fit Trainer over Toad. That's what Smash Bros seems to be more in Sakurai's eyes. We just need to roll with it, or just move on. At the end, it's pointless to whine as we're not the ones behind the game's character choices.