It also references the platform and the name (Dream Drop Distance). In fact, its very heavily parallels COM:

COM takes place in b/w 1 and 2 | DDD takes place in b/w 2 and 3

COM and DDD are on Nintendo Portables

COM and DDD have Sora and RIku as main characters

COM and DDD take place out of the normal realm of light, COM is in Castle Oblivion -> Realm of In between, DDD is realm of dreams

COM and DDD use experimental battle systems, COM used card system, DDD uses an improved deck system, deck system originates from BBS but is the evolution of the card system.

DDD sets up KH3 the same way, COM did for KH2 (Introducing the Organization 13)

The actual reason DDD is not numbered is because its not Sora's story, yes things happen to Sora, but like COM, its not plot related and serves as build up for KH3 (Specifically, Sora and Riku's Mark of Mastery Exam, and why they are the way they are in the beginning of KH3, (spoiler alert, look at the clothes sora wears in the KH3 recent gameplay trailer as well as his keyblade), and How Xenahort is starting up his plan) <- both things already mentioned at the end of KH2.

I say the plot is weak as a concession, I personally didn't mind that nothing really happened, and what happened to Sora nad Riku was pretty engaging.

At the same time, this is what happens when you mix Inception AND time travel.

Well, if you do the math: Kingdom Hearts 1.5 + Kingdom Hearts 2.5 = Kingdom Hearts 4, so  knowing Squeenix' trolling history,they will actually make us wait a very long time for that to ever happen!

So this is gonna tell what happened to Aqua? Yes please!

Yes. DDD is the "mainstream" knowledge of 3D, which is irrelevant to what I am talking about(Just the 3). Would love to cite because I only state facts, and while I did look for it, it pains me to say that I could not find it in my KH sources when I read it the day it was released(like all the interviews), which was in 2011 prior to the games release and after the 3D-DDD explaination. Thats what happens with the interviews as the years go by.

Unfortunately, I have to settle for the poor man's version of it in 2010, so here it is:

"Though it is still a tentative name, we have included 3D in the new Kingdom Hearts game title. It also includes "3", which implies that this may be the third iteration of Kingdom Hearts.

http://www.khinsider.com/news/Nintendo-Conference-Nomura-Talks-KH3D-2583

Hope that satisfies you because it didnt for me. *sigh*

I was going to correct a few statements you made which Nomura likes to change his mind on, but I'll let it go since I only wanted to mention 1 thing, which I did.

I think you guys are complicating things. 3D is a prelude to KH3. In terms of gameplay - freeflow and story, setting up the events. Do you need to play it to enjoy KH3? Probably not. It doesnt advance the plot massively(though its not like coded or days who are side stories), but has good moments, some answers and presents the setting for the sequal. 

I would say its about as relevant as BBS, maybe a bit less, but it adds to the main story. Its not a side story.

Ya see, you just described COM.

I would have preferred it be all seven games.

The gameplay of CoM is nothing like KH2 though. ^^

And the story itself wasnt as relevant, even if it was relevant. I dont want to enter spoiler territory here, but the events that transpire in the final chapter of 3D are something a KH fan wouldnt want to miss (espeically KH2 fans). Its closer to a mainline title than CoM was, but they do fill the same purpose. You have my agreement on that.

Or they may come to Playstation Now if Square Enix/Disney are smart but Kingdom Hearts games have never been released digitally so I don't know how probable this is.

So how long before KH takes Street Fighter's throne for most non mainland titles released in a franchise?