Just asked a guy we know who worked at Disney event photography up until very recently and he said getting photos in wedding outfits in the magic kingdom is now mega tricky. If you're a Disney Bride as they call it, no problem, a number of packages allow you to wear your wedding outfits and have a dedicated shoot. If you DONT have a Disney wedding, you can't do those shoots any more and other ways round like different shoots wont allow wedding outfits.
Apparently the next best is an "engagement portrait session at MK". They don't allow wedding dresses at MK again but not everyone wants that anyway.
They seem mega weird about wedding dresses these days. Back in the day we wandered round MK for the shoot, we spent ages at the grand floridian and went to V&A all in our wedding attire.
One of the cutest moments was as we were having some photos taken on the staircase at the GF and a little girl and her mother came out of the lift. The little girl dragged her mother over to the stairs and said Look Mommy a real princess! Will she go to live in the castle now? sweet :)