mdd,
If you read Rav Broyde’s essay you will find that there are more opinions that say that haircovering is d’rabbanon, and even a few (three, to be precise) that say it is simply a minhag.
Also, wigs seem to have disppeared from the Jewish world for a thousand years. They returned in early modern times in imitation of European gentiles.
ofcourse,
I know of at least one American rabbi who forbade wigs: Rabbi Isaac S. Hurewitz, in his Yad ha-Levi.