I would expect there are licencing issues, both with the park itself and the various sponsors around the park, that would cause legal delays. Rays would possibly be more challenging as it would require both Rays and Yankees to sign off on it. There would probably need to be 2 versions of Steinbrenner Field.
It's one thing for a fan to create their own replica that only a few would get to play and would likely be (even if very slightly) inaccurate, as opposed to the game having an official replica of a ground.
It does amuse me though that SF's ground has a giant Coke bottle, yet Atlanta's ground has a generic brand of Coke advertised (Cola-Cola I think it is).