Also, I completely agree with
NairWizard
that playing against Bayo completely drains the fun out of Smash 4. As a Rosa main, I actually don't mind playing against bad match ups like Cloud and MK. I enjoy fighting Sonic. Heck I'm biased, but I enjoy fighting against Rosa even with my secondary characters. I'll admit I don't have a great deal of fun playing against Olimar, but that's pretty much it. And besides, how often do you actually encounter Olimar... but Bayo? She's everywhere, and she's the worst of all. Ugh. Have to play super defensively and cautiously because of Witch Time, can't stuff her recovery, her up-b/down-b is a get-out-of-jail-free card in so many situations, she gets insane rewards for doing so little and taking such small risks.
Disclaimer, I don't really play her, so if I say something out of line, call me out.
I agree with your gist here, but I feel like you're missing an important factor in Bayonetta's gameplay. She certainly gets absurd reward for rather simple tools, even compared to the rest of the top tiers. Her recovery is very strong in distance, safety, and flexibility (altogether it's probably the best in the game, though that hinges largely on her keeping her second jump; I was aghast when Salem survived Larry's FAir to footstool combo). She can turn a disadvantaged situation into an advantaged one better than any other character because of her combo tools and Witch Time. And yet, she her neutral still feels rather weak (at least compared to some of the other top tiers).
Bayonetta doesn't exactly have safe approach options. While her burst options are fantastic her mobility is overall middling, which makes it hard to get in, especially horizontally. FAir 1 is relatively safe on shield (thanks enormous hitbox), DTilt is a good poke, and dABK, while a strong option, isn't nearly as good as it was prepatch and is telegraphed as a straight approach option. As good as her hitboxes are, she lacks the mobility to abuse them. Her grounded approaches (mainly Heel Slide) can be stuffed because of their poor frame data. She doesn't dominate in neutral like, say, Sheik or Diddy, and isn't great at forcing approaches unless your name is Ganon.
Yet, she somehow manages to control the pace of the match. I feel like this stems from the potency of her combo starters, especially up close. It almost feels like she's a zoner (is it possible to zone without area-controlling projectiles?). Approaching
her is nerve-wracking, because of how hard it can be to escape her vortex once you're in it. Yet it can be done. Characters with strong projectile games can somewhat exploit her mediocre approach options, and sword characters can outbox her large hitboxes. Fast characters may be able to break through her CQC and rack up damage (Zack's recent losses to Little Mac players may reinforce this in an odd way). This leaves most of the top and high tiers capable of dealing with her, but the lower down you go on the list it gets more likely that a given character will struggle with her.
I do believe she's the best character in the game based on reward, flexibility, and diversity of options. She, in a lot of ways, isn't exactly playing the same game as everyone else (Bat Within, while occasionally exploitable, is a poor choice to implement for preservation of the source game). She can absolutely be frustrating to play against. But she's beatable and has yet to show that she's an absolutely dominating force that can't be conquered.
Random note from watching EVO grand finals: Bullet Arts give her one of the best ways to consistently neutralize Diddy's banana.