This is... err... yeah. Honestly I sometimes wonder how much downvoting should have even been a thing. Like the rules say, indifference should not be a downvote, and honestly some of the more likely reasons, i.e. regarding moveset or style or whatever, are easily countered with "dude, its PMBR. They got dis."
Really, I think downvotes come down to the personal assumption that the character in question actively impedes one's enjoyment of the game, presently or in the future. THAT SAID, I will place myself in the camp that someone who is deliberately downvoting because they think that character's inclusion is over-representing a series/is potentially a cause for the under-representation of a favorite series... is legitimate. It seems like we can mostly agree that a downvote is fair if the user feels that the character's inclusion would personally negatively impact their experience... well, for some, a large part of Smash is being an All-Star series. And having fair represenation is a big part of their connection.
Trust me, Lyn, for example, can bring plenty of her own merit to the table. But so can everyone else. Again, PMBR. Has. Got. This. I promise. Just about anybody on this list can have awesome unique gameplay if they want. So frankly, saying a character, who could cause over-representation of a series, is keeping a character, who could extinguish under-representation, is valid simply because, well... yeah, Lyn can add a totally unique gameplay. So can the other guy. Don't forget, we only have limited slots, and I certainly would vote in such a way as to maximize the chances of my personal list making it to the top.
I mean, yeah, alot of the above is subjective... as it will be. This is a simple poll that is based, in the end, on the popularity, however justified, of characters possibly up to bat for new slots. If this is causing issues... well again, given how the system works, I would say the downvote itself is as much to blame. Its a kind of funky idea, since its supposed to say "well, I don't just think this guy isn't as good as the upvotes I picked, this guy is TOO subpar." Except for some people, its what is best or bust.
Whatever. I have no real stake in this. I like who I see, and the only thing I could care for actively trying to push won't happen anyways (sorry Hector.) I'm just saying, the downvote is a weird tool that probably is more trouble than it is worth.