I wouldn't. Imaginary animals was always a part of the original vision of the park. If they did it with ONLY current IP, then I would complain. But Dragon Tower, Quest of the Unicorn, and the Fantasia boat ride would not have been out of place in my opinion. Certainly no more so than Camp Minnie-Mickey.
Everyone likes to poop on Beastly Kingdom and I will not have it. It would have been, and still would be, great. But it can't exist now as it was originally planned because of Avatar (stupid decision), and even if they built it somewhere, they would have to have current IP all over it.