I don't understand why time and effort and money is being spent on dumb "immersive" bullshit
I do not see why it is hard to understand: some people, most likely the developers included, like that "immersive bullshit", so they consider it as important as the other stuff you mentioned.
Personally i am not a fan, if anything, i see most UI/HUD elements as a representation for your character's senses, like pain, alertness, a sense of surroundings, etc - ie. i do not see having a little 'alertness level' icon above an NPC's head as my character actually looking such an icon, but a representation for being able to read subtle body/face movements and aural cues that are hard or impossible for the game to communicate to the player - especially for games where the character's skills are supposed to be of greater importance than the player's skills. But i do understand them spending time on it because there are other elements i like and would most probably "waste development time" on, given the opportunity - such as physics-based interaction similar to that in Frictional Games' games or seamless interactivity with in-game panels like in Doom 3.
None of those are necessary in a strict sense, but they dress up the game to make it feel better (and yes, you may not consider all the elements of that 'dress up' important, but a game isn't made just for you). Without that sort of dress up, games would be just Excel sheets where you'd type your numbers and calculate the outcome (and i'm sure there are people who like to do just that).