Like the others have already stated that combo shouldn't even be effective at this point unless you're missing a brain.
You also have to consider mixing up your escape options when caught in her combos. For example if you're going to SDI and use dodge the entire time she'll read that. If you SDI in one direction the entire time, she'll read that. Her combos will rely on reads.
The same can be said for her too. If she doesn't use mix ups in her combos or uses the same one constantly she can be read.
Plus there's the fact if you screw up a combo and the opponent easily escapes they'll be waiting for you and your now laggy landing. While she may have a few easy combos she has more advanced ones as well which you really want to shoot after more and also require more skill and the ability to read quite well in order to pull them off correctly. The harder ones are tougher (obviously).
There's a lot of characters with extra recovery options. Also, ROB can technically do UP B, Jump, and UP B again. So can Yoshi.
Are you going to say they break the rules, too?
Bat Within is only useful in certain situations as well and depends on what you intend to do with it. While it can put her in a better position you can always do something stupid to bat within an attack and still get hit or even grabbed or whatever as well. You can't just attempt a bat within and expect it to keep you 100% safe. It's only as useful as the user makes it. Besides Bayonettas dodges are actually pretty terrible to begin with. Along with that you still have to time it to get bat within too, as that can also be mistimed.
And her dodges are really no different from others read wise. Read her dodges and take into account bat within.
Aside from the fact her counter is no doubt the best in the game, by the end of the day it is still just a counter. Her Witch Time can be read like any other counter, plus if used incorrectly it actually leaves her open to a counter attack. It also hates multi-attacks. If the Bayonetta doesn't think properly after a Witch Time the multi-attack can hit her and bring the opponent out of it, or clang with her Smash Attack if she wants to do that for some odd reason which would sort of waste the Witch Times potential really.
And lets not forget you can't Witch Time a grab. If you have a character with a super good grab Bayonetta will hate you. And don't forget you can't counter a projectile either unless you are close enough to them. The only exception would be Bayonettas Bullet Arts if not one or two others I think. So yeah, it might be the absolute best there is but it's still just a counter that suffers from misuse.
And how useful it is depends on the opponents placement and the situation.
Also, at the end of the day she is still a Bait & Punish character who has a not so decent neutral and lacks a few approach options. She can be easy to pick up due to her pros; however in order to make her shine you have to dedicate yourself to her and actually get good with what she has to offer. She also requires you to actually read quite well in order to get her punishes in properly.
Don't forget she is also light weight herself. Also, there's also this:
Her recovery only ranks 4th best in the game despite everything she has recovery wise.