Lucky lol I wish my wish list would stop getting royally stomped on

Byleth probably would have been better received as the second or third character in the pack.  People would've rolled their eyes and said "sure, of course" before looking forward to the next one.  I think positioning another Fire Emblem character as the grand finale after such massive surprises as Persona or Banjo-Kazooie was their real mistake in all this.

I'm not even upset about Byleth, TBH.  As far as flavor-of-the-week Fire Emblem protags go he at least looks unique to play and not just like Marth #5.

It's more the fact that after everything else in the fighters pass was so unexpected, unique, and lovingly crafted it can't help but be a let-down that a year's worth of build up led to the safest, most obvious and uninspired choice they could have possibly made.  "Fire Emblem sword user" is literally the biggest community joke about a bland, wasted space.

It's like if you had a meal at a high-class restaurant where the first four courses were all amazing gourmet dishes, and then for dessert they just gave you a Twinkie still in the wrapper.

You're missing the point. Videl doesn't have superhuman speed like everyone else. Like Koop said, it's a way to give her stuff that everyone else can do that she can't. I don't even remember if the manga ever showed her shoot a single fireball, she only has the control to fly.
It's not meant to be balanced, but it's still lore compliant, it's not like Xenoverse where you can teach here the Kamehameha.

Or even Heihachi.  Mappy, maybe.  Something else besides Pac-Man, at least before we get a 3rd or 4th rep from another 3rd party.

Then how do you explain Tails not even being an assist trophy?!
Shadow and Knuckles at least got to be assist trophies, but Tails didn't even get THAT luxury.
If you ask me, it's not Shadow and Waluigi who have been done dirty, but Tails.

speaking of music who sang the main theme in both english and japanese?

But... Toyotaro wanted a short cameo by Vegito.
Vegito Blue failing to kill any form of Zamasu for any reason other than undoing the fusion would have been really terrible. They're not going to do a fanservice cameo of someone that's supposed to be way more powerful than anything if they're just going to toss him in the fire by saying actually he's a big loser who fails to kill Zamasu.