More importantly, focus healing would seriously imbalance the game -- I suspect that's why it was removed.
Exactly what I think, it's pretty balanced as it is now.
There is focus self heal that gives up to 2600 focus every 6 min and if that has cool down, just sit down for 1-2 min, and/or use occupation products (Larvester) or eat a flower (OP).
(A bit off topic but, I still think the xp cap should be higher, I hit it so easily especially while digging in team.
It makes no sense then to improve the dig technique further, it makes digging boring for me.)