I don’t know….
When I was in high school, Philly boys, Long Beach boys, Ner Israel boys, Telz boys, all wore colored or striped shirts, and learned day and night, with passion and Ahavas Hatorah. Today we have all white clad bochurim, yet, the level of hasmada AND the quality of learning itself went down significantly. Sure, there is yeridas hadoros, but, when one starts focusing on the trappings, rather than on the core, those become more important. This attitude later pervades the shiduchim scene, as well. It is a sad state of affairs when one’s level of learning and piety can be “easily” determined by the color of his clothing, the width and tilt of his hat’s brim, and by how long and white his Rosh Yeshiva’s beard is.