Khalidov is at 185, so he doesn't fix the problem at heavyweight, and even then he is 35 now, that ship has realistically sailed. I agree they should have signed him, and you are right they don't always pony up, but that just isn't the case at heavyweight. If the UFC aren't signing them, someone else would be, but the fact Cup Chieck was their heavyweight champ and that the division is practically forgotten for the amount of fights it gets, tells you all you need to know about the landscape at heavyweight.
As far as deliberately letting the fight frequency fall at heavyweight goes, I think you have a distorted perspective. The UFC in the last few years has put on more fights than ever, despite slightly scaling back this year, but I don't think there have been less heavyweight fights than before, just that there are significantly more fights in other divisions. What this does is bring down the % of fights that are heavyweight bouts, but doesn't decrease the actual number of fights, they just feel fewer and are farther between.
Any org wants heavyweight fights, but expansion hasn't been possible in that division like it has been in lighter weight classes, because these guys just don't exist in higher quantities. Specifically in the case of Werdum vs Cain, yes, it is obvious they want Cain champion and perhaps tried to push the title fight onto a card in Mexico, but I don't think that is indicative of the whole division. Can you provide some samples of guys cut easily at heavyweight, because I'm drawing a blank.