Not to squash your enthusiasm, but those characters weren't all that popular during the era of the Brawl poll (Ashley is ehhh... debatable), Rosalina was still like a year away from her game even releasing.
I'd say the best sign of Sakurai still referring to Brawl-era popularity is how he specifically stated Mega Man's inclusion was based on his position in the Brawl poll.
Don't forget about Villager!
As unique as the effect is it's actually a rather poor representation of that character. It's like if Pokemon Trainer was somehow hypothetically relegated to 'Cut' or something.
Well we do have Ness and Lucas using PK moves they don't even use in their own game. Regarding "Push" though I feel it would actually work quite nicely as a neutral special especially because we could fit many of his other Psyenergy attacks into the other special moves as well as normal moves. His sword could also easily be used in normal attacks. Possible use of a summon for FS as well. That pretty much takes care of anything except the Dijinn (which I honestly don't see working in both a plausible and unique way at this point.) I don't know about you but this seems like a fine way of representing him.
To be fair, Japan and not Japan aren't exactly equal in Sakurai's (or Japan's) eyes, the bias rarely goes the other way. Though Isaac used to be a perfectly popular character there, and Sakurai has been known to use old popularity, so who knows.
It's not like the abundance of new c-list series would necessarily be a good thing for those still in question, roster space isn't unlimited. Now that Starfy got deconfirmed it's like people were expecting all the ATs with a possible chance to get in all together, or none of them. This doesn't effect the other ATs one way or another, they aren't all tied together in Sakurai's mind.
And to be fair, Starfy wasn't that popular in Japan. More than here, yeah, but it's not like his Smash fanbase was huge or anything.
Not for me. Every AT getting in would be highly unplausible. My early roster only contained 3 of them who happened to be the ones I thought had a good chance with a combination of things such as popularity, uniqueness, impact, etc. (Isaac, Starfy and Little Mac) I certainly didn't think they would have a much better chance because they were ATs at one point nor did I pick them because they were AT's. I would hope other people did the same.
Also, yeah it wasn't huge but it was higher than Isaac's popularity over there. My thoughts were that with the few true "all-stars" left that Sakurai might try and branch out to some new series and if Starfy was in fact the 2nd most requested new series (and also C-Tier according to Chronobound) over there than maybe he could have made an impact. Not to mention that the characters he was beaten by seemed to be from well-repped franchises already so I thought he had a good chance. Not great, just good.
Again, when Sakurai was compiling the roster, regardless of actual chance, series like GS, S&P, and Starfy weren't as inactive as previously, they had all had games in the preceding years; all had post-Brawl iterations.
Plus, look at Metroid, when it was first included in 64, it hadn't seen any game that whole generation, and it was popular during its NES and SNES heydey, yeah, but not crazy popular, especially in Japan, which was the sole intended audience for the first Smash. Yet it still got included, likely because as a series it still left a relatively large and notable impact, even if not a recent impact.
Metroid is a whole different entity as it was actually included at a time when Nintendo franchises were actually quite scarce (when you consider Smash was released at the end of the 64's lifetime). No Pikmin, No Golden Sun, No Animal Crossing, No Starfy, etc. With the exception of a few "retros" there really wasn't all that much other than what was included in Smash 64. Nintendo has added like 30+ franchises since then. I get what you're saying though but honestly the only series that I felt have made big impacts since then are Pikmin, Animal Crossing, Wii Fit and the Wii series. And maybe just maybe Golden Sun. Ironically, 3 of these have been added to Smash already.
Even if we could sadly at this point it wouldn't really matter.
Don't be deterred by the heavy amount of dialogue at the beginning, it picks up. Have fun!