A beckishe (a.k.a. a “frock) is a style. It’s popular with a lot of frum Jews since we tend to follow our own “sense of fashion” and aren’t influenced by what the goyim wear, at least not all that much. The region modern Orthodox stopped wearing long coats (of various sizes) was that King George V stopped wearing them in public (about 90 years ago), and that set the fashion for the modern world – almost immediately “short jackets” were “in” and long jackets were “out” for weekday and “Shabbos/Sunday/Holiday” dress. Something similar happened to hats about 50 years ago (by then the American president set fashion standards).
Since we don’t give a hoot what the goyim are wearing, we never get the message that long jackets were “out”, though a lot of the more modern have picked up on over the last 90 years.