I'm with you on this one. While I can see the appeal of an online Mirage Arena, I find most people's disappointment a little funny. KH was never, and has never at any point, been about multiplayer. It is a single player experience. Single player experiences are a dying breed. Every game nowadays has multiplayer tacked on to supposedly "extend the life of the game", but hey, who the hell is playing Bioshock 2, Arkham Origins, Metal Gear Solid 4,Tomb Raider, Dead Space 2, etc online to this day? Anyone? Most people agree that these games could have been better had the developers not spent their time on the multiplayer. Handing the mode off to a different developer would have been ideal. Tomb Raider and Batman's online modes were made by different devs and everyone agrees it's trash.
Oh and has anyone tried to platinum these kinds of games? It's quite enjoyable. *sarcasm*
So basically, people want a less polished 2.5 and an even further delayed/watered down online KH3 for a mode they'll only touch a handful of times. Yeah, that's rich.