Hearing is one of our senses, one of our ways to receive information about surrounding world so of course good audio helps with immersion and allows to feel game's world better. But as OP said lot of games don't put much effort into this sadly and this is especially true with many games here.
I personally always enjoy when game has pleasant soundtrack. If it's is completely soundless or have no background music I play with some ambient from YT running in the background that matches game's style.
As for other sounds it all depends on the game type and style. If you have let's say some sort of VN or other genre focused on static pictures and text, decent background music in anything you really need. But when there are some real-time interactions, combat or stuff like that it all feels odd being mute, so full audio is appreciated.
One thing I can skip and personally don't care about are full voiced characters. And that's because getting good VA isn't cheap. And when game is supposed to be voiced by some random person with average voice and zero acting skills... Nope, thanks, I'll keep to just reading plain text. Apparently many devs have same perspective cause most games here have only moans when it comes to actual voice acting.