One of Judaism's main principles is that we must remain distinct from the nations and cultures around us. This is mentioned several times in the Torah as well as the need to maintain a level of kedushah while doing so. Taken to its limit, it means that Jews should be distinguishable from non-Jews even at a casual glance. Our dress, our style of walking, our speech and other facts of our public appearance should distinguish us as b'nai Yisrael. Some legal codes go as far as demanding that we use a different colour of shoelace than the folks around us.
However, this principle does not exist in isolation. There are additional factors to consider, such as not appearing ridiculous in public. The halacha does not demand that we become laughingstocks to those around us. If a particular thing Jews do draw ridicule then we need to cease from doing it in public. We are the people of God and if we act in a way that draws mocking, then we are also drawing that mocking towards God.
Furthermore, we are not only supposed to be laughinstocks, we're not supposed to be stupid. Once in a while, the non-Jewish world comes up with a great idea or two, one that improves comfort or health. To avoid such ideas based on the need to be distinct is stupid. Is there anyone out there, for example, who avoids toilet paper because gentiles use it?
Finally there are the parameters of the rules of being distinct. From whom are we to distinguish ourselves? Just anybody? From general culture or from specific ones dedicated to idol worship? If a particular type of clothing is worn in society simply because it's common and available, not because it represents a faith, creed or belief of any kind, is it still forbidden?
All these questions are dealt with in different ways by the various groups in the Torah-observant world. At one end you have the left-wing Modern Orthodox (LWMO) who treat the need to be distinct with great leniency. Outside of a postage stamp suede kippah and maybe a hamsa necklace, there is little to distinguish members of this community from the general public. From one side this is a bad thing. There is nothing specifically Jewish about their appearance. On the other hand there is nothing specifically gentile either, just a non-specific appearance with no deeper religious meaning.
At the other end of the spectrum you have the ultra-Orthodox (UO) who seem to make the focus of their religious practice the need to stand out from those around them. Their dress, style of walking and speech is specially tailored to be inclusive of only their community and to exclude everyone else. A recent speech by an important Chasidic rebbe-to-be, as covered in this article, demonstrates this point:
Rabbi Hager said in his sermon that the students must "beware of the dangers hiding on the street." He added that, "a student who wishes to delve into Torah studies and observe mitzvot must detach himself from all nonsense and not let them infiltrate."
The rabbi called on students wearing modern metal glasses to remove them and move to anti-modern plastic glasses. Rabbi Hager also spoke out against yeshiva students wearing contact lenses.
According to a Hasidism source, metrosexual men and students of the modern Lithuanian yeshivot were the only ones wearing contact lenses.
"This is the reason why the rabbi called on the students not to wear them. We are well aware of the statement made by the former Vizhnitz rebbe, who said we must wear the exact opposite of what is worn in Paris."
The problem with such an extreme position is that it almost immediately begins to undermine itself when examined. First of all, where does avoiding what the gentiles do end? The gentiles use electricity and running water. Should we avoid those? The gentiles wear clothes made by machine. Is it back to the loom for us? The gentiles use toilet paper. I'm not even going to go there! It is quite clear from even a casual glance at the UO community that when it comes to bathroom hygeine one is indeed content to imitate what them gentiles are doing in Paris.
Furthermore, while one can certainly appreciate the idea that Jews should not ape the latest international fashions but should choose clothes based on Jewish principles of decency and modesty, one can also understand that dressing in just any long sleeved outfit isn't so easy to condone either. Basing one's behaviour on doing the opposite is not much different than straight out imitation. In both cases, one is following another example to decide one's own behaviour.
And for me this is the biggest problem with the extremist attitude expressed in the article. Yes we must remain distinct from those cultures and ethnic groups that surround us. However, by basing that distinctiveness on the principle "those shalt do the opposite of those around you" we are actually allowing non-Jewish culture to determine our behaviour. There is enough positive in Jewish culture to allow us to conduct ourselves in a different fashion without having to worry that we're not "different enough" from the gentiles around us. If we are to be an example to the nations, as the Torah tells us, it should be through such a positive expression of the faith instead of a reactionary "we'll do the opposite just to be different!". The former is a true expression of Judaism while the latter is just a cop out designed to fulfill the injunction of distinctiveness without putting any real thought into what God might have meant by that.