Does the endowment size directly correlate with generosity of financial assistance?

Why would a college have an NPC that gives overly pessimistic estimates that would discourage many potentially desirable applicants from applying?

If its FA has a significant preferential packaging or semi-merit aspect that is not stat-based, it could set up its NPC to give a range reflecting that some applicants with the given financial (and academic, if asked) information could get better or worse FA than others.