Bayonetta teaching people how to play the game properly and thus being a good thing literally defeats itself as an argument for the character. If other characters don't already force you to play in this (alleged) proper way, it means Bayonetta is the only character who clearly creates that need. Therefore only Bayonetta's opponent has to play properly while she herself doesn't (unless it's a ditto). It's literally the difference between top/high tier and mid/low tier, the former can throw out options relatively freely while the latter actually has to actively think about their and their opponent's every move.
Those are all skills you need to play the game successfully, it's just that in the past they weren't skills you needed when fighting low to mid level players (into which I'm including myself, so it's not like I'm talking about "those scrubs over there." The problem, as it were, is that it forces people to learn this at a lower level of play than what is normal, and that it's possibly unpleasant to do.
There seem to be two different discussions about Bayonetta (actually more, but I'm going to narrow it down): How does Bayonetta affect low to mid-level play and how does Bayonetta affect high-level play? They're both things to take into consideration, in terms of balancing, etc., because competition doesn't just consist of the best of the best players, but I think this distinction often gets blurred in arguments.
For example, over the course of Melee vs. Brawl arguments, there would be this back and forth where Brawl players would say that their game is more thoughtful, and then Melee players would say that Melee has just as, if not more, thinking involved in addition to the difficult mechanics and such. The difference was that because of Brawl's mechanics, it made being able to read and out-predict the opponent a necessity even at lower levels of tournament play, whereas, according to Tafokints, a Melee player could potentially get top 32 at a national just off of mechanical skill.
"Fighting Bayonetta" looks to be something like the equivalent of "Learn Melee tech," a barrier that presents itself at low to mid levels of tournament play that encourages some and discourages others. Thinking about it in this respect, I wouldn't begrudge someone for not wanting to bother to master all of Melee's shenanigans in order to play the "real game," so maybe I haven't considered people who don't want to deal with Bayonetta to play the "real Smash 4," whatever that means.
At the same time, I think it's weird to call Bayonetta a bad design because she was designed with very deliberate weaknesses that essentially lay a blueprint for how to defeat her, even if the blueprint isn't completely reliable at the moment because of how strong she is.
A few weeks back, I mentioned the idea that Bayo makes top tiers feel mortal, because while in the past they could get away with a lot of things due to superior frame data, Bayonetta punishes them for thinking they're 100% safe. As
Trifroze
says, though in a more negative light, it's something that lower tier characters have to deal with on a regular basis. Is introducing this element to more characters necessarily a bad thing then?
But what about Bayonetta? Why can she get away with so much? Isn't she just the new top tier super safe character? Even though she can do things like retreat with After Burner Kick, Dive Kick safely on shield, etc., her frame data is such that she's meant to be punishable after missing. Like I keep bringing up her rolls and dodges because they are LITERALLY the worst in the game in terms of cool down. Moving through the air with her special moves isn't just good, it's NECESSARY because her standard defensive techniques are bad.
Whether or not she needs tweaking, I think that it's clear where the design intent is for her character in terms of both offense and defense, just from seeing how her rolls and such work:
1) If you attack her too early, then she has a frame 1 semi-dodge (frame 3 for rolls), which cuts down the effectiveness of your attacks
2) However, if you anticipate her dodge/roll, then she's more vulnerable than anyone else in the game (slightly worse than Samus's)
If you don't attack her when she expects an attack, you're supposed to be able to capitalize. That means, how important should it be to Smash Bros. to have the control to not press buttons?