In many sources on the subject I have found that the manner of dress of Yeshiva Bachurim in pre holocaust Europe was that of mainstream society. The look was one of being clean cut for that era. Most recently this was illustrated on the website of Dr. Yitzchak Levine with photos of Gedolim when they were Yeshiva Bachurim or even older. He stated in an e-mail correspondence that, in Slabodka or the Mir in Europe, they would not have been allowed to look the way Yeshiva Bachurim of today look.
I, also, have in my possession a film of pre holocaust Ponovezh with a very young looking Rav Kahaneman and many of his Beis HaMedrash Bachurim. All were nattily dressed in stylish clothes of the era. Tzitzis tucked away, clean shaven, no Peyos and were wearing light colored hats. I have spoken to various Charedi individuals who are knowledgeable on the subject and I was told this look was purposeful on the part of the Roshei Yeshiva. Bachurim were in fact forbidden to look frumpy. They were also forbidden to emulate the “look” of a Gadol or Rosh Yeshiva as this was considered Yuhara (which means showing off your Frumkeit in a self serving non L’Shma manner).
Fast forward to today. The look is uniform and nowhere near stylish. It is unique and often sloppy. There are exceptions. Some Charedi Yeshiva Bachurim do look quite sharp and dress as stylishly as they can within the parameters of the Yeshivhse dress code. But it is more of an exception than a rule. In most cases, the young men... many of whom are big Talmidei Chachamim look a bit disheveled and in some cases, like they sleep in their clothes.
The mind boggling question is... what happened? Why have things gotten this way? Why were the Roshei Yeshiva so Makpid that their Bachurim look more modern? Why were they more sensitive to what the parents and other Jews think of their Bachurim? Why was this important for them and not for our current Roshei Yeshiva? It is as though the Musser is in the exact opposite direction. Today’s RY are more concerned that their Bachurim look as different from the rest of society as possible. Today's Roshei Yeshiva want their Bachurim to have their own distinctive look... to be Porush from society as much as possible with seemingly utter disregard what the rest of Jewish society or even a parent thinks. They seem to care little about what impression a Bachur makes on the rest of the world... as long as he conforms to the "look”.
It is as though there are two totally different Hashkafos at work. The Torah world of the past which, ironically, is so glorified by the current "Right" was in fact polar opposite on this issue. The Roshei Yeshiva of yesteryear literally forbade the current Yeshivishe look of Peyos, beards, and white shirts and dark clothing, and black hats. THEY FORBADE IT! Today the exact opposite is happening. The more "modern" a Bachur looks the more he is looked down upon and encouraged to conform. No serious RW Yeshiva Bachur would be caught dead wearing a stripped or colored shirt. The attitude is so pervasive that women in seminaries are indoctrinated to be suspicious of such Bachurim who do not wear “the uniform” for Shiduchim.
Maybe the reason is Niskatnu HaDoros. Compared to the previous generations of rabbinic leadership, they need greater influence and control... and the Chitzonius of dress codes helps establish a more insular society wherein they can exert that control.
