> > Maybe it could be moved to mode-specific menus
> > that support facemenu?
> 
> Yes, that'd make sense.  I guess it's basically
> only enriched-mode where facemenu makes sense?

I've replied to this at least once.  No, it's not
only enriched-mode that makes use of facemenu.el
code.  Not at all.

In particular it adds menu `Text Properties', which
lets you add/remove/describe/change/... text
properties.  See attached image (vanilla).

And I've pointed to library `facemenu+.el', which
extends menu `Text Properties'.  See other attached
screenshot (and note that there are also submenus).

Enriched mode is a small part of what facemenu offers.