Losing Pogba one year after losing Vidal sets a dangerous precedent. It just indicates to clubs out there, that our top players are available if you can lure them away. We need to be able to hold onto our best players if we want to be considered an elite club. Yes, 100+ million is a lot of money for Pogba, but from a business perspective, it is a bad deal! We have completely and totally revamped our midfield in 2 seasons! That sort of turnover (usually) isn't healthy.
Also, there are those who are trying to comfort themselves (and convince themselves), that we are better off without Pogba. Only time will tell whether you are right or not. It just irks me when some people automatically hype/overrate a player simply because he is now with Juventus, and severely underrate another because he has left this club. All this Pjanic + Higuain > Pogba (well, no $#@!! Two players are better than one) is ridiculous/ludicrous, petty and childish.