Harav Yosef Shalom Elyashivzt”l believed that it was more praiseworthy for a woman to cover her hair with a kerchief than with a wig. In his words, “Since the wearing of a wig is questionable according to halacha, it is definitely preferable to wear a kerchief since this is a matter of halacha.”
And in a letter written by one of his top tamidim Rav Karp it says:
“Many times, we heard from Rav Elyashiv zt”l, how pained he was by this great breach of tznius,
and how much he encouraged Jewish women to go with a mitpachat, which he considered “Glatt” , because even the old wigs, were a matter of controversy among the poskim, and from then on to today, the Yetzer Hara has not rested to produce different styles of wigs, the common denominator of which is to stimulate the Yetzer Hara and cause the men of Israel to sin, and it is a double obligation for us to cast aside this pritzut, and for sure anyone who is a Ben Torah– Heaven forbid that he should be lenient in this matter–
and let this be the first stringency that he takes upon himself, especially as (today’s wigs) can create a Michshol for the Rabbim (a pitfall for the masses). And “Ashrei” (fortunate/blessed) is one who separates
himself and who REFUSES to allow today’s wigs into his home. And in this merit, he will merit children who are Talmidei Chachamim and Tzaddikim.
(I have this all in hebrew but for some reason when I copy and paste the Hebrew it doesn’t post)
It’s ALL about beautifying and making oneself attractive outside – that is the entire issue with most of todays sheitels. And natural looking wigs fall under that catagory too- they are beautifying just by the fact that they look like the woman’s hair! And hair is beautifying