Organizations that live on indefinitely- governments, universities, churches- don't give up land almost as a rule. One or two hundred years from now, they might really need this or that plot, and it could be nearly impossible to acquire then.

One easy to appreciate example are universities & other schools holding (& sometimes leasing) land adjacent to them. If they didn't, in the distant future if they need to expand, some scalper or holdout could cause large problems.