I personally skipped and found Coded irrelevant because of its retread status (also I didn't have a DS. I was a poor high schooler back then). Of course looking back now, all the segments between the retread are probably going to be important but I'm still pretty apathetic toward this title.
I rate CoM higher than Coded personally purely because I found interest in the story segments in between the retread worlds.
I think a lot of fans skip or completely write off games like these two because of how much focus they put on retelling worlds we've been to sooooo many times before. Even when it's a new way to tell the story, most of the time I feel nothing. I've already been here, y'know?
So in that way, if Nomura and team were worried about sales, I can understand why they'd decide to slide in something important at the end to make sure it doesn't flop or something. I don't think he needed to worry about that with MoM though. People LOVE KH music with or without context. This could've been an arcade style self contained game with no plot relevance and people would've still bought it.
In future side titles, like CoM, Coded and even Days I think, I'd like to see them introduced new worlds if they're going to be plot relevant anyways. Pull a BbS or DDD and put us in a new location even if there's some familiar characters along the way. I think KHUX is the first retread-like game that used a whole new world.
Use the lesser known Disney properties and go wild. Stuff that's been buried for decades that isn't racist and/or homophobic and give it some spitshine.