Maybe it's deemed an unnecessary "extra" thing. Something you add on when you feel like indulging those you interact with, with a bit of pleasantry.
Maybe we just forget what a big difference a bit of politeness can make.
A lot of people see great importance in being very direct and forthright in how they talk, but they don't seem to know or care that you can be frank without being rude. You can get your point across And have a bit of basic politeness at the same time. They're not mutually exclusive. You don't have to sacrifice common decency and respect in order to be honest or direct.
Who knows??