It's done for all economy buildings and factories now (mass storage and hydro will be added in the next version), so its rather consistent already. Since the whole concept of hp differences is new, applying it to combat buildings too would probably be even more controversial, and could also much easier cause balance problems than with the eco structures.
However if the hp differences work well in general and cybran becomes too weak with this changes (which might very well happen), applying a low amount of regen to the other buildings (that have less hp, or will get it) can be considered. The regen on the eco buildings is an extremely small advantage right now, there isn't anything bad about it, and the reasoning that a disadvantage (lower hp) should come with an advantage if possible is very true, but we mostly added it because people were requesting it.
But idealy dont do that and rather fix repair function (that is already ussles) and make cybran repair stronger as other faction when want this kind of faction diversity.
This is actually another good idea to give cybran an advantage in return, and probably better because it can actually matter in more situations, at the same time it's something you actively have to exploit too. I like it.
And fixing the repair system is planned anyway, just, as with many other things, we can't do everything at once.
When we get to changing the repair system, we can look at this again.