Think about that this is probably not Gaga/Katy decision, but whoever makes the marketing for it. It may very well be that AMAZON decided it, they are the ones interested in getting people pre-ordering from them. And what a better way to do such thing as making something exclusive that you can get only pre-ordering from Amazon. So, Amazon probably had the idea, and decided to do this with Katy and Gaga, they suggested to them, both accepted, done.
Don't take things too serious. This is just marketing. And to be fair, it worked with me since i pre-ordered just because of that, probably worked also with a lot of you. And will work for Katy's fans. And worked for AMAZON since they got a lot more pre-order sales than otherwise would.
So Katy is not allowed to promote a special edition but Gaga is allowed to create 9 hours long playlist to preserve her Top 6 chart position? is that your logic?