I've spoken about Tznius (the Orthodox modest dress code) before, here and here. I've written that since I believe (with perfect faith, as Maimonides wrote,) that the dress code is based on G-d's commandments, that I don't have a problem with questions of sexism. G-d is not a sexist and therefore the dress code that He created cannot be sexist.
Tznius (or Tzniut) is more than just a dress code, though. It also includes a code of modest conduct. I choose to think of it as a royal code of conduct. G-d chose the Jewish people to be His chosen Nation, His firstborn child, and since G-d is the King of all Creation, that makes us all royal children. Along with the privileges of being the children of royalty come serious responsibilities, and that includes a strict code of conduct.
Not that I would compare the Jewish People's spiritual royal dynasty to theirs, but for the sake of discussion, let's take a look at the British royal family. Most people, when they think of the Queen of England, recall seeing her in suits and hats at all times, following a royal dress code that commands respect for her majesty based on her royal position rather than on how trendy her outfit is.
The same goes for her demeanor. She does not demand respect through a loud voice and outlandish publicity stunts (can you say, "Paris Hilton"?). She keeps a calm and collected persona in public because that is what is expected of a woman whose social position itself commands respect and veneration.
It is similar with the Jewish people. Our social status and existence is not based on the opinions of others. If it was, these "others" would have finished us off a long, long, time ago.
Rather, our status in the world is based on the fact that G-d chose us to be His nation. We have survived all this time with our dignity intact solely as a result of G-d's will.
Based on modern psychology, the way that the Jewish people have been treated for thousands of years - as dirt beneath the feet of the gentiles, - one would expect us to have serious self-esteem problems. How often do we hear about how African Americans have less chances in our society because they were treated as slaves for hundreds of years? Yet we, the Jewish people, who were treated worse than slaves for thousands of years, don't seem to have a problem climbing the ladder of success in the secular, gentile world. Why is that?
Because we have known throughout the years of torture, denigration and murder that no matter what the nations of the world think of us that we are still G-d's chosen nation. Like the Queen of England's position, society's opinion of the Jewish people cannot change our royal status. They could treat us like vermin all the wanted; in the end, we rose from the extermination camps and built new lives, new communities, new shuls (synagogues), and new personas of beauty despite what they thought of us and all that they did to us.
Like the Queen of England, then, we should remember that we don't need to show off our bodies - whether by taking off our clothes or by running down the street yelling, - to gain the respect of others. We can carry ourselves with dignity because we know that no matter what that person driving by in the fancy German car sees when they look at us, their opinion cannot change who we really are.
Seeing us as vermin didn't stop us before and it won't stop us now.