There is a spirit of the law. It does not say 6 inch red shoes are not okay anywhere, and I applaud you for not wearing them.
Ok, you are correct, there are certain modes of dressing I would criticize even if they are not against the letter of the law. I would even fault someone for not having the sensitivity.
I suppose what irks me here, is that there is nothing inherently untzanua about wearing a sheitel. Chazal say that hair of a married woman is ervah, she is not showing her hair. Now, I don’t see any extreme insensitivity to tznius involved in wearing a sheitel, so I don’t think it is right to criticize people who do it.
Also, the OP seemed to be basing him?her?self on the assumption that chazal would have banned it, or even more absurdly, on the fact that chazal did not expressly permit it (since they did not exist in current format). It is almost as if the OP is trying to read an actual issur into chazal which does not exist.