It is ironic, but it's a logical move from a business standpoint. Mickey wasn't to be as heavily associated with the first Kingdom Hearts if it wasn't a success, but since it was they want his merchandise ripe for the picking first - poster boy privileges. Anyways, the vast majority of Disney resort visitors would prefer Mickey merchandise over Sora, no contest.
At least for now as the test the waters, it makes sense that they are only putting in the really well known characters. However, if they ever made an Aqua pin...my life would be made!!!! Highly unlikely since after the Disney cast they'll move onto Sora and Kairi (a pin with the 7 PoH would be amazing...or the Station of Awakening platforms???) and then probably Riku. If we are lucky after that we'll get Roxas and Namine. I don't see TAV or any Org. pins happening...well, really ever.