minhag - Doesn't the wide use of Sheitels among Orthodox Jewish women prove that hair no longer retains the erotic status that it once had?

In reading scores of halakhic material on the subject of kisui rosh le-nashim throughout the ages, I have found that there are essentially two views as to the nature of the obligation for a woman to cover her hair in public - that it is an actual law (לאו) of the Torah and that it is minhagh (מנהג) of Jewish women. While it seems that these two views were once mutually exclusive (i.e. one side permitting the uncovering of a woman's hair in public and one side prohibiting it), today they seem to have merged into a view that although due to hergel (הרגל) in seeing womens' hair it has lost it's status as `erwah (ערוה) they are nevertheless required to cover it (cf. Arokh HaShulhan 75:7 & Igroth Mosheh, Orah Hayim 1:42).

During the discussions of permitting some (in this case more than a tefah but less than all) hair or all hair to be left uncovered in public, the point is usually stressed that even if someone did hold that it was a subjective obligation, they are stuck in a bind since the local custom is determined by the practice of religious women and not irreligious or non-Jewish women. And, so the argument goes, since the overwhelming majority of religious Jewish women cover their hair, the obligation - even for those who may hold that it is determined by custom - is still binding today.

However, the way in which the overwhelming majority of Jewish women today cover their hair - either all or part of the time - is by using a sheitel/wig. So, especially since the sheitels today are so realistic, worn long around the shoulders, and are even at times made of the woman's own hair (!), doesn't that communicate that the religious Jewish world is essentially fine with women's hair showing? Doesn't that invalidate the need for covering at all?

I have been told that the actual isur is seeing the actual hair and not hair in general, but this seems illogical and with this logic we could say (halilah wa-has) that nude pictures of women are okay to look at since it is not actual `erwah, etc. Which, of course, is blatantly ridiculous to any religious Jew.

So doesn't the wide use of Sheitels among Orthodox Jewish women prove that hair no longer retains the erotic status that it once had and that the halakhic obligation for women to cover their hair in public has been nullified?