UA manages inventory to maximize yield, not to placate GS members. If there was no GS level, I doubt it would have much of an impact on inventory management. Ultimately, I'm fairly certain having fewer people around who purchase the last minute high fare/full fare tickets is a bad thing, not a good thing. I fail to find your argument compelling.
Precisely. UA's RM team actively manages inventory made up of booking classes that have absolutely nothing to do with the frequent flyer program (though of course you can earn more miles on the higher booking classes yet this isn't part of the day to day demand analysis that the pricing and inventory yield analysts do for their assigned flights). A GS member or someone with no status can still buy the same last-minute F fare.