well
when you consider, that under the CURRENT gamma mechanics, terraforming is not an everlasting change of the terrain,
the old structures would have been reverted by now anyway.
Those who have used the terraforming charges back then, also have benefitted from it for the time the old system was up.
Asking for reimbursements is a valid thing - but its also up to the DEVs to decide if the work they have to put in to reimburse it, after setting up some rules and conditions, is actually worth it.
If you think, they HAVE to do this, then you should also think about examples like the broken orange NPC aggro on follow bots. Do they now need to remove all and everything from the game that was generated by "exploiting" this now different game mechanic?
edit:
I haven't got my "Interference beacon extension" reimbursed either, after CRM decided that its bad that i can use it to shoot walls. And now, after we can shoot walls, they didn't revert the stupid LoS restriction either.
*Disclaimer: This post can contain strong sarcasm or cynical remarks. keep that in mind!Whining - It's amazing how fast your trivial concerns will disappear