Long story short, the amount of time something exists has no bearing on how much people enjoy it.
Well, of course you can enjoy a new game. But we're talking about bonds to possibly completely new characters.
As a maybe weird example:
Of course you could like new friends and maybe have more in common with them than with old ones, but all the history (experiences and times together) from the past ones should probably be worth more, until you've had enough time with these new friends (aka more games of a character and some years of playing them).
I'll use Decidueye as an example, since it's one of my most wanted newcomers (third, in my case). Ghost, Grass, Fairy, and Normal are my favorite Pokémon types, and Decidueye covers two of those, being a Grass/Ghost type. Owls are also some of my favorite birds, alongside toucans, ducks, and pigeons, and Decidueye is an owl. Some of my favorite fictional characters are archers, like Virion from Fire Emblem Awakening or Hawkeye from The Avengers, and a true archer is something I've always wanted in Smash (beyond just using a bow for a neutral special and then never firing it again). I also love Pokémon. As a franchise it means so much to me. I was born in 1996, right when Pokémania was about to hit the US, and I remember loving it from the start.
So the fact that Decidueye is a Grass/Ghost Archer Owl Pokémon (with a nice earthy color scheme to boot) makes it instantly appeal to me, and it's one of my absolute favorite starter Pokémon, rounding out my top four after Venusaur, Greninja, and Samurott. And of course, its abilities also make it a standout Smash contender in my eyes. Yeah, it's not my favorite Pokémon, but considering ones like Klefki or Shiftry or Chandelure straight up won't happen, why wouldn't I support a Pokémon I love that still has a chance? Just because I haven't loved it as long doesn't mean I love it less, so I give it my support.
I can definitely understand this and it's the same for myself. I like many of the new Pokemon instantly if the design looks good or cool to me. It's also Pokemon, which is a franchise I like that gets more and more new characters. Completely new franchises I'd see as something different, though. Pokemon also (usually) keeps all new Pokemon and treats them all as about equal. It also became the norm to include some new Pokemon every time, which makes sense. As a comparison: just because Pauline joined in Mario Odyssey after not being used too much you probably shouldn't expect her to appear in Smash or other Mario spinoffs immediately. A new Pokemon is a much bigger deal than a "side"-character. Same with Elma or Rex/Pyra from Xenoblade.
Since the Xenoblade series has already etablished itself it's expected for it to get another character to join Smash. Since they're important/main characters it's also okay for them.
But will your bond really be the same as for a franchise that had more games and reoccuring main characters that you've known for years? Idk. I mean if you like the other game more then sure I can easily see it.
Another big thing is timing. For characters of series with non-static casts, like Pokémon, Fire Emblem, or Xenoblade Chronicles, or small series with a recent game but no real future, like, say, Code Name: S.T.E.A.M., it creates a now-or-never scenario. If they don't get in now, their series will likely move past them, shutting the door on them to enter Smash for the forseeable future. If Decidueye doesn't get in now, he's not getting in ever, as the next Smash game will be long past Alola. This isn't even something that only affects new characters either. Celica, my second most wanted character and third favorite Fire Emblem character over all, has been around since 1992, but only last year was Fire Emblem Gaiden remade as Shadows of Valentia. It had been in development since mid-2015, so it isn't a total lost cause...yet. DLC isn't even a real option for her either, as Fire Emblem Three Houses is around the corner and they'd likely opt for Byleth or Edelgard as DLC instead. This holds true for Decidueye vs a generation eight Pokémon as well.
So a character can be truly popular despite being new, and in many cases, the now-or-never factor is also at play, so why should it be held against them if they're not "supported long enough" if it may result in them never getting in at all?
Oh I'm not against giving characters chances just because they weren't supported long enough. It's mostly just "do people REALLY like this character more and did it exist long enough for that to be possible and have made a big enough impact that's enough to be worthy of joining Smash?".
This isn't right at all. Just because someone enjoys a character that you don't see as "worthy" of support doesn't make their support any less genuine.
Is it really genuine support for the character (imo no, but you can see that in many different ways)? I can definitely sympathize with wanting characters or whatever that would make other people happy, but I don't think this is always the case. I think many people are just supporting some characters "because it's the current fad" or maybe they like the char a little bit and since they have more followers it'll get bigger and seem much bigger than it is, making them more confident or seem like they want that character more than others.
I remember during Brawl I didn't want to Lucario to join and was worried about Mewtwo after seeing him. People really wanted Lucario a lot, but once they found out about Mewtwo not being in the game they were like "wait, I wanted Lucario, but not if it meant in replacement of Mewtwo". Many characters have a lot of follower or seem big, even enough many people might even like many other characters more.
I think that's another reason why I'd support a poll of your top 3-10 (or whatever number they'd use) favorite characters for the poll.
This will make it easier to find the most wanteds overall.
Since maybe [random example] 20 people have K. Rool as 2nd and only one as 1st, but 3 people have Dixie as first, but all others have her at like 10th+. But from the way the ballot was done, this wouldn't be shown and Dixie would seem more popular.
