old man,
I see that we can finally put to rest the idea that one must “dress his best” for every davening.
I’m not sure that anyone here was arguing for dressing one’s “best” for weekday davening. I think there is a difference between dressing one’s best and simply dressing up.
Therefore, the yeshivish way is only one of many ways to dress for davening, and the insistence on it is socially driven and nothing more.
Regarding specifically black hats and black jackets, I agree with you completely. Some do hold, however, that a jacket and hat are required for davening (and others do not). As gavra_at_work has been pointing out, even this requirement does not stipulate a specific hat and jacket, so what constitutes a respectable hat and jacket again goes to the culture of the community, but this is a somewhat different concept from the cultural “uniform” described above.
And yet, I have been the tenth man in a yeshivish mincha minyan (not in a yeshiva) more than once and watched them wait until another person dressed like them showed up before starting. But we have ten! Sorry, only nine.
This sounds like a horrible experience. I am sorry.
For the record, I wear long pants,a buttoned down shirt, and shoes.
And a kippa or some other type of head covering too, I presume?