tier lists still say fox and falco are the best characters, and most of the pros who say that spacies aren't top tier anymore are old melee veterans who main spacies
if you say "just buff everyone" you get 2.1 ike, 2.1 lucario, 2.5(?) sonic, 2.6 ivysaur, etc... it sounds nice in theory, but then you'll end up having to either homogenize a lot of playstyles amongst characters or else you'll have to stupid stuff like "well, ganon doesn't have a good neutral game, so in exchange, he'll kill you at 20 with any aerial." /hyperbolebutstill
The CT tier list was made just a few months after PM 3.0 came out, and is disagreed upon by a good chunk of the community. Plus you have to remember that it's also based on how frequently players placed well with their mains; spacies are still up there only because people have developed their metagame that far and so many people play them. Given a few years, people of other mains may come close to that degree of know-how with their newer, changed characters. But several characters already have far more potential than spacies.
Even then, one of the biggest reasons why spacies were top tiers was because not many characters have an answer to all their tools; all characters after Jigglypuff on the tier list (maybe excluding Yoshi and Pika, now that we know what their tech is more capable of) were made unviable at top level play simply because they can't handle the spacies, and maybe a few of the other top tiers. In PM, there's several characters that can hard counter fast-fallers (and by extension spacies) now, if played correctly. They no longer have nearly as much control now that the cast has been buffed with tactics to counteract the spacies. They're just like everyone else now - some good MUs, some bad, but mostly even. They may have more good MUs than most right now, but that's just because they've had years to develop their Melee meta. Other chars just have to catch up.
So yeah...simply buffing the rest of the cast is a pretty significant nerf to them. Jigglypuff is another top tier that hugely suffered from universal buffs; stellar recoveries make her entire meta way less viable. Compared to the rest of the cast, she's not even all that viable in PM at all anymore, despite having 0 changes between the Melee --> PM transition herself. On that note, the frames for power-shielding being increased from 1 to 2 is a huge difference as well, and is a huge tank to Falco's laser game. It doesn't sound like much of a difference, but it definitely changes too level play.
That's what I meant by buffing the cast. Obviously I don't just mean given buffs to the extent that they destroy any MU; their moveset/aspects of their playstyle should be improved just enough to deal with the MUs that that had hard times winning in previous games, and obviously against the others being buffed.
