It mostly has. Chorus Kids is by far the most popular Rhythm Heaven character, but enough people chose other characters (and specifically not them) that its noticeable.
Chorus Kids are an anomaly in that they aren't really a character that would ever develop organic support. It's a totally out there idea that we got a sneak peek into, that some of us got sold on and others were not convinced on. I think if we ever got Chorus Kids properly implemented into Smash everyone would be down, but knowing so little about how this could have panned out means we'll only be as excited about it as our imagination lets us be. But I can understand why it never became the centralizing frontrunner, because they're not like... that kind of character, you know? Most people are going to rush to try and find the most consistent character, the most definitive mascot, etc which is hard to pin down for this series.
That is to say there's probably a contrast between those who support a more abstract idea like Chorus Kids, or characters that they can more directly visualize as fighters like Karate Joe and the Wrestler. Specifically the former as he appears in every game in the series. I didn't vote for Joe personally (just not as silly as I'd like a RH character to be) but I endorsed the Wrestler, Barista and Yuka as well. I'm down for pretty much anything but Chorus Kids really won me over for how intuitively they could adapt what makes Rhythm Heaven special. Simple goofy little guys, they're in a trio so it opens the door for a lot of 1-2-3 rhythm attacks, they are musicians...
I wish we could have seen the world where they were lucky enough to make it, and we all praised the creativity behind this choice, but instead about 50% of people think it's cool and another 50% probably think it's a weird bandwagon pick that has somehow lingered around for all this time. The leak is the only reason we're talking about them, but it's also the only reason anyone has a problem with them. That's how I feel, at least. It's like if "Mr. Game & Watch" was leaked, never made it and we were supposed to come to our own conclusions about what the hell that entails.
Do these ramblings make sense lol? I just feel like the Chorus Kids inhabit a space completely unique to them, as such a strange concept that we probably should have ever really known about in the first place. So that's going to translate into community support in a somewhat odd, uneven way.