That is one of the most fatalistic, bass-ackwards, and anti-conservation ideas I've ever heard and am quite shocked that it came from a long-time HT mainstay like your self, who has clearly articulated some very well thought out ideas on conservation in the past.You think that you can remove horses and everything will become paradise. Deer, antelope, elk everywhere. In truth. Just a few more cows. Nothing else will change.
Just because it won't turn into a Valhalla of big game species, equivalent to the pre-colonial times, doesn't mean it's not worth doing. That idea alone run counter to EVERY SINGLE conservation project, action, and goal out there. Perfection will never be achieved, but should not hinder good projects.