Since their introduction, Citadels shoot out of the ground like mushrooms. To prevent Space littering and senseless grind in undefended space, i would like to see some sort of a decay System for Citadels.
If not fueled, the Citadel looses it’s Shield layer and so the whole first timer.
If not fueled within the next 3 Months, it loses the armor Layer and invulnerability window. Can now be attacked and destroyed any time without timer.
Yes, it would need some more commitment from Citadel owners in the form of logistic. But since the price is a not very useful tool to prevent Citadel spam and would mostly hurt smaller groups, it’s the best way i see to tackle that problem.