That's honestly your problem that you put your emotional baggage on a character that Sakurai thought would work better to be NPCs
Maybe if you guys didn't villainized the AT concept, there wouldn't be so much negativity
And you are forgetting that you guys want so many potential upgrades, and there is only 5 slots left, even if there where all upgrades in this pass, you guys would still be incredibly disappointed
Lowering expectations =/= killing your "hope"
The villainization is "this role sucks". It's not about disconfirmation entirely. People hate not simply cause they're not playable, but it feels like a slap in the face too. Just like Mii costumes are some kind of butchering of a character. Which is more closer to what the AT issue is. People consider playable the most important role, and anything but can be a slap in the face. I agree this particular mindset is poor, but the series was made on "the biggest playable characters duke it out", so it's kind of the game's own design where this comes from.
But more importantly, the negativity comes more from shoving it in people's face that their favorite character has no chance. This is the issue people have. And when they're accused of being in denial? Well, what'd you expect people to act like? They're going to be quite aggravated.
So it doesn't mean if people like AT's or not. It's people refusing to even acknowledge things aren't that simple and DLC can change stuff as is. Spring Man actually being playable isn't really change expectations moreso than throwing a tack into the face of "lol not happening" people, something that improves speculation. When that's no longer a valid argument, that means it's less likely to come up. Of course, this is also solvable by people not worrying too much about roles and dropping the constant need to bring people's hopes down. ...So an unlikely scenario. They keep their expectations generally in check anyway. That's hardly an issue like you're making it to be.