Why would one choose clothing as a way to express his personality…
Even among western men’s clothing variety, there aren’t that many ways one can dress. For women, a discussion about where a woman “bought that” can be had because there are millions of different designs… Effort is put into women’s fashion. Women definitely express themselves by their clothing choices and outfits.
For men it’s basically either a polo shirt, dress shirt, jeans, slacks, cotton pants or a suit… Men don’t have “outfits” and “accessories”. Men also generally hate shopping for clothes, buy whatever is good material, looks good at first glance, and move on.
Men don’t express themselves very much in the way they dress, except when they want to be rebellious, feel that the Torah world “isn’t me”, or want to blend in with goyim.
If a yeshivish guy feels stifled by the dress code… Ask them, do they write? Sing? Dance? Paint? There are many ways to express one’s self, but all too often, the answer to all the aforementioned questions will be a resounding “no”. True expression isn’t something that they’re interested in doing.
It’s just an excuse to want to be more modern.