While it is hard to see how a real-looking sheitel could possibly be erva l’maiseh (it DOES cover the hair after all), I don’t see why it is so hard to accept that these types of sheitels lacking in tznius. Yes, tznius allows for, and encourages being attractive, but when you are so attractive that you begin attracting improper attentions, that is not ok. There is a line (and we can open a new forum to debate what that line is…)
As someone said before, the yetzer hara really has brainwashed us with regard to sheitel, r”l. While the ideas behind head-covering after marriage are complex and kabbalistically rooted, there is still an over-riding aspect of tznius- a married woman has to be even more careful about tznius than a single woman!
Also, why does everyone think tichels and snoods equal ugliness? I have a great collection of tichels and snoods, and my friends always compliment me on them, and I feel good about how I dress. Anyway, sheitels are horribly uncomfortable.
We take too many shortcuts in tznius- shortcuts that we wouldn’t dare to take in any other area of our observance. Tznius is not specifically written out in the Torah, because the Torah lives and breathes tznius in every word, and because it is a spirit more than a cut-and-dried set of rules. We should live our lives that way too, and dress in the spirit even when we can find the loopholes. We should be zocheh to bring about the geula through careful observance of tznius.