In a blue sky world, I'm thinking it would be better to seriously rejigger how the game plays and pare it down to a 30-character base roster. This would require some tough choices about cuts that would inevitably piss people off. But here's a few easy ones to start: Dark Pit, Lucina, Ike or Roy, Palutena (no one likes her), Pac Man (fine for one game, otherwise a good cut target), Lucas (even though I like him better than Ness, but probably only need one Mother character), Rosalina (Mario needs some cuts), Dr. Mario (same), Lucario or Mewtwo (don't care what anyone says, these characters are quite similar and Pokemon needs cuts), Zero Suit Samus (nest her back into Samus), Mii Fighters (**** em'), Robin or Corrin (pick one recent FE avatar). Also, lose Cloud, Ryu, and Bayonetta (don't need to be in more than one game, don't really jibe well)
All of this talk sounds like someone who has no concept of the Smash competitive scene. Some highlights:
-Ike and Roy are extremely different characters, as one is all about massive knockback while the other is about optimal close-range damage with a long-range option.
-Rosalina's play style is known within the FGC as a puppet master, and arguably makes her the most unique character in the Mario roster of fighters.
-Mewtwo's appearance in Smash 4 only highlights how different he and Lucario actually are, as they possess vastly different play styles.
-Zero Suit Samus is superior to Samus in every way and the two characters play nothing alike.
-The DLC characters have some of the most unique play styles for a competitive player to utilize, and 2/3rds of those mentioned were fan picks.
Now, as for your personal preferences, such as calling out a certain goddess of light... Well, I like ARMS, so who am I to say you have no taste? But in all honesty, she's one of my favorites, so I don't get the hate.
Smash isn't like any other competitive fighter and there's nothing wrong with that. It defines its genre (platform fighter) by offering an immense amount of variety in play style and function. The argument regarding clones is legitimate, especially since some of the clones in Smash 4 are unlike Falco in the sense that they have relatively few differences from the character they are based upon on a fundamental level. Lucina's reach, run, jump, and float speeds are
exactly the same as Marth's, the only difference being that one character can deal tipper knockback and damage while the other can't. Dark Pit is a bit slower and heavier than Pit, but not by much- the main difference comes from their special moves. The same can be found in Doctor Mario's slightly reduced reach. However, the better thing to do with these characters in a future entry is to make them more unique. Say what you will about the fall of Falco since Melee, changing his basic attacks and down-B have only made him more distinguishable from Fox. Roy's updated look and moveset are now much different from Marth's, and that's a good thing.
Smash 4 wasn't perfect, but it possessed enough positive changes from Brawl and a competitive metagame that was different enough from Melee that it stood on its own two feet, even if the DLC characters pushed the meta in a direction that I personally feel did not benefit the scene. I think the thing that mostly everyone can agree on is that Smash 4 introduced a lot of characters that had very unique play styles: Rosalina and Luma, Little Mac, Shulk, Duck Hunt, Pac Man, Bowser Jr., etc. If those characters were to be cut, I would be pretty disappointed, especially since the recognition for those franchises and characters has only grown since their inclusion. Please understand that this is also a party game, at least, in Sakurai's head, so having as many Nintendo franchises represented is important for people who just want to play as their favorite character and throw a Bob-Omb at their friend's head.