I agree with stage size. I think ceilings are fine, better than before actually. I dunno if you saw the picture, but someone did a comparison and it showed 90% of stages with the same exact ceiling height. That aside, Stage sizes and layouts are more toxic for running away than people seem to realize. Like I don't think people know how truly nasty Skyloft, Rumble Falls, etc can be. The legal stage list is probably going to shrink as people play better imo. It's kind of no wonder that old Sonic was running around for free, look at our legal stage list. Draculas, Rumble Falls, Skyloft, etc big stages.
Most of the cast can beat Ganon, because of a lot of factors. People in general:
1. Safer on shield
2. Better projectiles
3. Much MUCH better recoveries
4. At the same time, improved edgeguards and gimps on linear recovery characters
5. Onstage mobility for the average cast member is much higher, while Ganon remains relatively slow in actual movement
6. Average Grab range is huge in PM compared to Melee. Marth is no longer "special", should give you an idea
7. Average range/disjoint in PM is higher
Ganon didn't get enough buffs to overcome what the game has developed into. You need harder reads to accomplish the same thing you could in Melee, especially against newer characters. Falcon has issues with some of the cast as well, but he's obviously more equipped to handle the game by being faster/more mobile. DK is definitely better than his Melee version and probably fares the best out of that trio honestly.