I think we are getting caught up with how PDS used to be. PDS doesn't even have to participate in actual battle, it doesn't need to be a weapon it is after all Planetary Defence System.
My idea is to have PDS replace structure defence.
there are two functions of PDS one is protection for structures the other is a protection of roids
so as an example:
1 PDS reduces roid cap by .1% and protects 3 constructions.
you could cap the amount of PDS to 100 giving you 300 protected constructions and a 10% reduction of roid cap this will hopefully encourage more SK'ing as i would like to see it not be exclusive to war
I would have liked to see a return to how PDS used to be, but unfortunately i dont see that happening