I don't think they're that big a deal, especially when the geographically appropriate subspecies is hard to obtain. However, I think some examples are overdone, like Amur leopards in African-themed areas. If African leopards are too hard to acquire, I'd prefer zoos leave leopards out of their African areas altogether and instead put their Amur leopards in Asian-themed sections. But if they want to breed the subspecies and don't have anywhere besides the African area to put them or whatever, I understand that.