Tniut is a very tricky thing.
First off, there aren't clearcut guidelines on a lot of tsnius aspects. Which on the one hand makes it very tricky to know if you're doing the right thing, and of course allows for a lot of misinterpretation.
Tsniut is dependent on your community, your minhag and mostly your notion of what feels tsnius.
Personally, I have noticed my standards change depending on whether I am in chul or in Israel. It's not the length of my skirt or that of my sleeves that change. In general, one dresses down a bit in Israel. I just put on whatever mitpachat suits my outfit best (lets face it, no matter how dressed down, it still has to match) and that's it. Here in chul I'm much more conscious of what goes on my head, since I don't want to stand out too much. But besides that, I find myself wearing jewelery and shoes that I wouldn't wear in Israel. So yes, tsnius does depend a lot on whether you'll stand out or not. At least for me it does. My hoop earrings would really have made me stand out in my yeshuv in Israel, but here, they just make me look as fashionable as everyone else. Same goes for my high heals
But in the end, I think it's very important to remember that not standing out doesnt mean becoming invisible (as much as the critics of orthodox Judaism would like you to believe otherwise). Women are allowed to look nice, be beautiful even. Yes, sexy is out, but that doesn't mean you have to dress in a big potato sack and lose all your individualism.
I wouldn't usually preach about tsniut. Yes, I believe it's important, but I respect that it's a very private and as I have already mention, personal aspect of our lives that no one has the right to impose on anyone else. However, with the burka/shawl trend that is seemingly becoming popular in Israel, I feel we orthodox women have to take a stand. The above mentioned women hide the bodies and faces of themselves and their daughters and are seemingly ever more layered than their Muslim equivalent. Therefore, we should be telling these overzealous women and the rest of the world that this is not what Orthodox Judaism is about and that it is wrong.
In fact, people are outraged, the eidah chareidit has denounced this practice and there are lots of discussions going on. However, is it such a surprise that this is happening? The separation between men and women in chareidi society is bigger than ever. Pictures of women have already disappeared from chareidi magazines and newspapers. The name Tsipi (Livini) will not be used since it is too familiar. And during the elections, there were big problems with the posters that contained her picture. Is it then so weird that these burka women have gotten the impression that they are meant to not be seen and try to disappear all together? Is this not the same as young girls wanting to be skinny, because that is what they are being taught in their magazines?
Maybe this phenomenon should not merely be condemned, but rather examined closely. Maybe, it is an inevitable outcome of the shift to the right in the ultra-orthodox world. And maybe it is the wake-up call we all needed to tell us this must stop, not every chumra is for the better. And if we don't hear the alarm, maybe, just maybe in 50 years our grandchildren might actually be walking around like this.