“Considering that I have yet to see a rav kick someone out of a shul for lack of a hat/jacket, and considering the fact that I don’t know of anyone who has seen it, I would say that it’s not, in fact, common practice.”
I know of a shul where the Rav will ask you to leave if you are not wearing a jacket. It is minhag hamakom, in that shul the Rav wants to keep a certain respect for davening so he asks that anyone who comes to daven there wears a jacket. (He does not require a hat.) This is in a frum neighborhood with many other shuls so if you are “stuck” without a jacket you have other options for davening with a minyan.
“If the Yeshiva has a rule to wear a hat & jacket, one who does not wear it breaks the rule and has to face the consequences.”
There are some yeshivas where the rebbeim will ask a talmid to leave (or go to the Ezras Nashim) if he is not wearing a hat. Again, minhag hamakom. If you are in a Bais Medrash where everyone wears hats and jackets and you are not then perhaps it is better to daven biyichidus the to go against the rules. These are obviously b’nei Torah who always wear hats and jackets for davening so the few times that they do not have them it is better to daven biyichidus. I assume that this is what R’ Chaim was referring to.
“No lawyer would appear before a Judge in Court to represent his client without a jacket.”
Lawyers all wear jackets but they do not wear hats. Hats are no longer in style as a respectable way of dress. I once heard it explained that the yarmalkas we wear today are not respectable either. Would you go to a king with a shmata on your head? Therefore, since as Jews, we cover ours heads, it is better to cover it with a hat then with a yarmalka since it looks more respectable. On the other hand, nowadays, yarmalkas seem to be a normal style of dress and Jews nowadays who do not wear hats would have no problem going in front of a king with just a yarmalka.
“Wolf – What looks smart to you isn’t really of any great importance. No offence, but it somewhat comes across that you are more concerned with your own feelings rather than what the Poskim say.”
When it comes to respectable dress, perhaps it is more what people in that area consider respectable then what outside poskim feel. R’ Chaim wasn’t necessarily referring to MO communities when he gave his answer.
What would R’ Chaim say to the following situation? If a yeshivish guy is davening in a MO shul where everyone is dressed smartly with ties and jackets, but the yeshivish guy looks like a shlump with his shirt untucked, jacket over his shoulders and a dirty, smashed hat thrown lopsided on his head. Perhaps the yeshivish guy should leave and daven biyichidus rather than break the decorum of the davening. Perhaps he should miss the beginning of davening while he tucks himself in and makes himself presentable. I would even suggest that he ditch the shlumpy hat and daven without it!