Since circa v7.13 there's now read-only lo interface, which is correct since linux-based operating systems have it, but would be there an ability to hide it or remove in case it has not been used?

Just disable it.

Not possible, it's a hardlocked readonly device now

The loopback interface was always there (vital for some operations so removing it would very probably cause some problems), but was hidden up to recent ROS versions. So seeing it is a feature. I'm afraid you'll have to learn to turn the blind eye to it if you don't see any use for it.