Most games don't have the time budget for that. Visuals take precedence, and it's not easy to get to 60fps as it is, especially if you're doing a lot of other processing.
And stealth games especially will probably rely a lot on shadows and other visual things, which make rendering more expensive.
That's true, I just like when stealth games go beyond just player visibility, some of my inspirations do that:
- Thief Gold, sound was important, each surface would make a certain amount of noise, and you could damp the noise by covering the ground in moss, or reduce it by walking slower.
- Splinter Cell Chaos Theory: which had a sound-meter with 2 indicators, one for the noise you are making and the background noise. I specially like this system because of how it allows you to make much more well-informed decisions.
- Sniper Elite: you can cover the sound of your rifle with loud background noise in some maps, they are regular, and they have cue moments before the loudest part.
Not PvE, but Hunt Showdowns use of sound is worth mentioning. Like you mentioned, every surface has a sound and level, animals react to your sight and sound and will make their own noises, weather and env effects cover or uncover sounds, you can use items or gunfire or anything else to decoy. Really great. All a pvp game so you're trying to sneak up on actual people
And stealth games especially will probably rely a lot on shadows and other visual things, which make rendering more expensive.