I think they are going to be an important use case. Similar to GPG or ubuntu.

https://wiki.debian.org/Subkeys

I'd like to put subkeys in my kind=0 profile and have them "just work". I'd like to add them to the linked data schema which might be a step in the right direction. After a while multiple accounts becomes more useful, and I'd like to see multiple sub accounts, so that you can protect your master key. This might be a long way away, or need a next generation of apps, so I think I'm just going to start using them anyway. Maybe they will catch on!

https://github.com/nostrcg/schema/issues/6