A gartel is necessary for davening according to some poskim, and in one reading of the magen avrohom. Some litvishe, including rav boruch ber, grew up with gartels. He switched to putting it under his jacket in deference to his rebbe rav chaim brisker, who did not wear one at all.
when we see modern people wanting to be more outwardly religious looking, that is a complicated issue. Is it part of an upward trajectory? Are they in fact becoming more frum? Or is it just superficial…that’s something an individual modern person’s rebbe would have to talk with them about.
I took on wearing a gartel after asking one of my rebbeim; he said to ask my father if he’s makpid, which he was not, but that was the first thing he asked me to do, before even getting into my motivations.
streimels were most definitely not for weather protection. They were a badge of honor after the goyim made us wear funny hats to mock us. Rav shach says (merosh amanah) that wearing long was a mesorah which we dropped; the “pick your battles” type of thing, along with shaving. We’re not perfect, and you can’t make everything a red line. Chasidim did, in fact, make the chitzonius a red line, and they are successful in their derech.