Upgrade requests still represent cash value to the company as the airline books revenue from the frequent flyer division by redeeming the points. Staff travel is supposed to be only if space is available after paying customers are taken care of, and does not represent any revenue. Staff should not be allowed to bump out a paying passenger, even if they're only paying a smallish amount (class upgrades). If nothing else it's a bad look.

Note - I'm talking about staff leisure travel flying on a space-available basis, not staff who are repositioning for duty. I recognise that pilots have clauses in their employment agreements that may require business class travel, and because they sometimes get called last minute, this is one reason that upgrades are sometimes cancelled, or classic rewards downgraded.