I honestly don't see sex sounds adding that much more to the game.
There's people that want them, people that find them annoying and the majority is just indifferent to them.
Full voice acting won't happen, like ever, too expensive.
Moans and stuff during sex scenes is easier to do but also problematic...
And honestly, do wet slapping noises add that much?
As for Claire...
Eventually, she's not a main girl but apparently she will have more content than usual.
The important part being "eventually".
Viewing post in Corrupted Kingdoms (NSFW 18+) comments
Some people do.
Honestly, some minimal voice acting could do fine.
Having them react non-verbally to what is going on could improve the experience a fair bit. Without having to worry about hundreds of thousands of lines of dialogue.
But it would be really difficult to find someone to match Gramps' laugh...
As for gasps and moans.
Personally I always just turn them off.
You can hear the same generic asian girl moans for so long before you start begging for someone to shove a drill up your ears.
If I'm honest with you, I'd rather have more background music.
Different girls having different... "sex music"?
To match the feel of the scene.
But it's not that easy to find royalty free music that could be considered "sex music".
Fuck a duck.