takes deep breath*
Personally. I like clones
because they add variety to the game (hence I said variety, not diversity).
Like for example, say that you are playing Mario, and you are going against this Bowser player who keeps beating you because you're too weak. With clones, as opposed to having to enter territory that I'm unaware of (a different character), I can simply play Dr.Mario and solve the problem, since speed was never the issue.
Clones also help to add synergy to the roster. A good example being Captain Falcon vs Ganondorf... I can almost certainly assure you that both of these characters wouldn't be as popular in smash as they are now had they not been connected. Why? Because it's these relations that these fighters share that makes them so interesting. It adds meaning to the characters, in addition to creating a rivalry between them that would've never existed otherwise, which means that not only is it boosting their significance, but it is also boosting their competitive value.
Proof? Because Captain Falcon and Ganondorf have a clone-connection, despite coming from two series that are completely unrelated to each other, however if you look at Villager and Donkey Kong, these two are never mentioned in relation to each other, because their is no relation. They are simply just characters in a game. That's it. Nothing important, no connection, no rivalry. Nothing. And how interesting that these two characters are rarely seen in competitive play of any kind, whether it be on the couch with friends, or in a tournament.
Another important things is that Clones give players an alternative way to play as their character, which means that if Marth isn't working out, you can switch to Lucina or Roy (if he gets in), if Lucina isn't working out, you can switch to Marth or Roy, and if Roy isn't working out, you can switch to Marth or Lucina. They all work together to collectively create a solid, useful character.
Also, in a way, Clone characters are essentially the equivalent of a Custom Character, which means that by playing Dr.Mario, for example online, you basically get to use a custom moveset for Mario, despite the fact that this is forbidden.
Ultimately, Clones are good because they make the game, yet break the rules.
