I mean, you're not wrong.
Bayonetta is an excellent character, but the nerfs really reduced the chances you'll run into her (Especially her counter). She's not too bad, but we've got even better Bayonettas than ever, which is all I could ask for. Well, there are still counter spammers but there's no such thing as a perfect world.
Corrin's traits just exemplify awesome. To be fair, your can play as Marth, but Corrin's a swordsman AND a dragon. How do you get better than that? Long reaching moves, paralyzing projectile, there's literally no sense as to why you shouldn't play him/ her. Plus, Corrin has amazing tools that can shoot them to tournaments. Its very satisfying to just play as Corrin.
Cloud is popular, has a big dumb sword and can do a LOT since he has so many options. He's a versatile swordsman that has an answer to a lot of questions to his ganeplay, and not to mention he's CLOUD from Final Fantasy. That's unreal, and his name echo's the hearts of many gamers. He's great, and easy to play.
Plus, a major factor is that they're all DLC. Everyone's playing them, and they're really unique and have reasons to play as them, especially compared to their other DLC counterparts and already included smash counterparts.
They lived up to their hype as well, with Robin's runspeed turning away a lot of players, Roy was over hyped as his fundamentals were overlooked, even Marth himself since everyone expects him to be top tier, in which that opinion changed dramatically among other players.