I think Miami deserves a bit of a chance to see if a competitive team could bring fans in. That fanbase has been dicked over by ownership so often. If they had the Rays success, I think they'd draw better than the Rays do, but we won't know unless it happens.
I agree though, getting the Rays out of Florida and into a better baseball market would have been the ideal scenario. Even if they built a new stadium in Tampa, at least you could have spun that positively as it's moving the team to a better location. This is destined to fail. After the novelty of a new stadium wears off it will be right back to 10k a night. You see teams like the Reds and Pirates where clearly if they start to look good, then the fans will be there in droves. St Pete isn't that market.