UngeheuerLich
Legend
The low to hit is due to cr instead of hd determining the attack bonus of monsters and the way CR is used. That is not too bad actually. As player I don't like to be hit too much. 
I also don't want to hit through 1000s of hps and I don't want to hit only every otger day. As I now have insight as a player I think the numbers are quite good.
What helps in our games is that we really don't know when the next chance for an uninterrupted rest will arise. That makes expending resources and losing any hp feel like damage.
So until now there was no real need to up hp on a regular basis. Most monsters are tough enough.
What I noticed though is that in a larger group of 6 pcs there may be a point where it is indeed better adding hp and maybe increasing hit chance and damage for enemies because if you add too many enemies, they might still die easily due to area damage and they might kill a pc due to focus fire. And on top it also slows down combat too much.

I also don't want to hit through 1000s of hps and I don't want to hit only every otger day. As I now have insight as a player I think the numbers are quite good.
What helps in our games is that we really don't know when the next chance for an uninterrupted rest will arise. That makes expending resources and losing any hp feel like damage.
So until now there was no real need to up hp on a regular basis. Most monsters are tough enough.
What I noticed though is that in a larger group of 6 pcs there may be a point where it is indeed better adding hp and maybe increasing hit chance and damage for enemies because if you add too many enemies, they might still die easily due to area damage and they might kill a pc due to focus fire. And on top it also slows down combat too much.