That is true. You really do not know who those characters are that's on the bridge. I think some of them were more prominent in the first season and it's as if the writers forgot about them.
I get it though. Discovery did not have 26 episode seasons to dive into every character on that bridge and they did break up the usual Trek tradition of not having the bridge crew or the senior officers being the main characters. So they didn't have enough time in theory at least, to give them some sort of extended background story or development.
I say in theory because I am sure someone with more time than me could point out in each episode of each season where they could cut out some parts in exchange with some interactions with these background characters.
But really, if you think about it, the older shows didn't do that much with the characters outside the main cast or recurring ones like DS9 or Barclay. We had that engineer that in the second episode of Voyager got his nose broken and he appears randomly on the show. Nurse Ogawa had some nice scenes but not alot though she did get to sit in the conference room when she was being turned into I think a monkey.
Hell O'Brien could have been counted among those in the early TNG seasons until someone realized Colm Meaney could act!
