Oh I did. I like Roxas and co well enough but none of them are really stand-outs.
Kingdom Hearts doesn't sell for the original characters, I can say that with confidence, it sells for the same reason that Smash does. The novelty of your favorite characters and worlds of a specific brand being explored in a single product.
No I'm actually talking from experience. Everyone I've ever talked to about the game has sited Frozen, Toy Story, etc. for their reason for wanting the game.
If my personal experience doesn't do it for you, you can simply look at numbers. The original Kingdom Hearts life time sales kick out around 7 million, Kingdom Hearts II's sales kick out around 5 million, and Kingdom Hearts 3; which is undoubtedly the best selling game in the franchise, kicked out it's first WEEK at 5 million units. Meaning that anything past that point had a near 100% probability of being players brand new to the franchise.
I respect your dedication to Sora, and admire your admiration for the series, but just remember that the hardcore fanbase will almost always be the minority, vocal or not. Doesn't have to be 100% accurate but a lot of Kingdom Hearts 3's sales came from the casual, "I want to explore some Disney Worlds!", audience.
I've gotta disagree with both of your points here. While everyone you've talked to only mentioned being interested, everyone I've talked to about Kingdom Hearts III wanted the game to see how the current storyline ended..even if they only played Kingdom Hearts & Kingdom Hearts II (I advised these poor souls to at least watch story synopsis for the other games..).
Now did a lot of people discuss wanting this world or that world in the game? Absolutely, of course they did. Much like Super Smash Bros, speculation on what worlds or characters may appear is fun, but unlike Smash, the crossover isn't what people tend to care the most about. Most people care about Sora, Riku, Kairi, Roxas, Axel, Xion, Aqua, Terra, Ven, and all the other original characters. If people only cared about the Disney content, well, the series would likely have already died since they are typically beat for beat retellings of their original movies..heck, a lot of Kingdom Hearts fans are actually a bit annoyed that the Disney Worlds rarely add anything to the main storyline itself.
Mind you, I think those people are crazy because Nomura is a terrible writer and everything he's made after FF7 has been complete nonsense. But that's beside the point.
To be fair..Nomura was only in charge of Final Fantasy VII's art..he wasn't in charge of a game's storyline until Kingdom Hearts (though I disagree..but I could understand your view considering how confusing and convoluted the storyline of Kingdom Hearts can be..)
Sora I think makes a lot of sense, but the potential questions surrounding his license make Banjo Kazooie look like they were never bought out by Microsoft/rival company. Square Enix itself is a potential roadblock, not just Disney. Beyond that, we also don't know how much budget Sakurai has left; which does apply for all future characters, but it especially applies in this case.
Honestly, there's really not any questions about Sora's license, just a lot of confusion. Sora, and all Kingdom Hearts' original content, is entirely owned by Disney. Square-Enix only develops the games and creates the storyline while owning all Final Fantasy & World Ends with You content in the games (though Disney half-owns rights to any unique designs, such as Kingdom Hearts I's version of Cloud).
Disney has explained before that they own all of Kingdom Hearts' original content but when making big decisions regarding the series, they always consult Nomura out of respect.
So, if Sakurai & Nintendo contacted Disney about including Sora in Super Smash Bros, Disney would likely contact Nomura to ask for his opinion on it.
It really wouldn't be any different than any other 3rd Party in regards to difficulty and I'm quite honestly still of the opinion that it wouldn't be as difficult as working a deal with Microsoft was. Aside from consulting Nomura, Square-Enix wouldn't be involved in the deal at all.
In addition, since the new DLC Characters following the Fighter's Pass weren't considered in the original DLC Budget, chances are that Sakurai has a new oe increased budget with which to make them..so there's really not an issue there.