Comment 1 for bug 170324

The development direction is determined by many factors,
including difficulty of implementation, availability of the
underlying infrastructure in the codebase, and developers'
needs. In particular, what is "eye-popping" for you may be
absolutely essential for a developer (who is also a user),
and vice versa. If you want to affect this more, join the
development team.

As for this particular feature, implementing it requires
first implementing proper support for tspans, and that
requires implementing in-text selection UI which is
currently missing. All this is in our plans, but it's a
tremendous amount of work and we're moving towards it
gradually.