The PBN privileges that are left when you remove RNP APCH are minimal!
Especially for helicopter operations through a mix of Class G and D airspace, however it’s part of the PBN concept for reduced separation in ‘PBN airspace’.
Personally I think it works fine how it is now, that is to say you can only fly PBN routes and terminal operations with the qualification on the specific type. That way those who want to and are appropriately equipped can do so, if they maintain the appropriate training and checking. Those who don’t can’t. Those who can’t but want to will at least have reason to invest in the appropriate aircraft kit or certification to enable them to.
Once you have PBN on your licence how does anyone know whether you are maintaining PBN privileges on type with each PC?