Well, yes it is partially that(Rosalina, Doc and Daisy are all definitely less important than Toad overall with only Jr being an arguable after the main Mario cast of Mario, Luigi, Bowser and Peach) but there's a bit more to it than
just that.
Obviously Toad's been stuck as a hapless meatshield in the past, and now he's been upgraded to also be a throw. This is kind of cool, at least at first but then you realise Sakurai is intergrating Toad MORE into Peach's moveset so him breaking free of it and being able to go solo is going to be even more difficult as Sakurai has gone on record stating he dislikes alienating the playerbase by changing movesets too much.
This is pretty bad news for us Toad fans in general as it means Toads going to most likely be stuck with Peach for a good while longer. Then it got worse.
Then along came Daisy who ALSO uses (a) Toad. So now we have him pinned to two characters movesets which makes it an even bigger obstacle, one of whom is a more minor character than Toad himself and doesn't even have the connection Peach has to the Toads. Sakurai couldn't have changed the Toad to a Crazee Daisy or a...well anything else more fitting aesthetically?
We've had multiple characters who received a Mii outfit in Sm4sh being upgraded to playable; K. Rool, Isabelle and...Chrom. Chrom who was a move in the last game but went the opposite way to Toad becoming free of Robin and being his own character in this game. Palutena likewise freed herself from Pit's move and is deemed worth upgrading to playable. Yet...Toad who also recieved a Mii outfit's big upgrade from a move...was to being a special move
and a set of throws that will likely cement him in that role with Peach for games to come.
So far we've had Toad playable via a special move that Peach, Daisy AND Kirby can all use, a set of throws for the princesses and the Mii Brawler is allowed to dress up as Toad, yet no actual playable Toad.
This alone is pretty annoying but doesn't really make it worse than say Tom Nook, who is now Villager and Isabelle's Final Smash.
After all unlike Nook, we still have Captain Toad, who has just had a pretty dang successful video game released last generation and a successful Switch port of the game. A lot of Sm4sh's Nintendo roster were taken from notable games from the Wii generation after all so we were hopeful...and then he got deconfirmed as a part of the background in a screenshot on the website...he may be the only character to get that treatment as most were at least shown in gameplay in directs so everyone was made aware of his deconfirmation but the Captain got a very backdoor exit from the speculation scene. Some still think it's an easter egg and he's still playable but most people have come to
Personally I've been campaigning for Toad since Melee, but it's hard to get support even started whilst Peach has Toad in her moveset as she tends to get revealed pretty early on. People just gave up, I guess?
Captain Toad Treasure Tracker is the most relevant any Toad has ever been but now Sakurai's not drawing newcomers from recent games like he did for the most part in Sm4sh.
Based on that I've laid the ground work to get more people on the Captain's side for future Smash games by producing this:
This is all I can do and it's far from perfect but with 245k views at current and 12k likes to 201 dislikes I think it may at least help. Honestly the moveset needs tweaking still, for example; I'd rather Boos instead of Mudtroopers for the upsmash for example as they'd make the move a lot safer since they can be placed higher and won't break the game if Captain's on his platform when using it, but it's a good start I feel.
I think I may have waffled a bit. Sorry about that, I'm in a bit of a rush!
