An apt comparison I couldn't have made until Current Year is that the big numbered Kingdom Hearts games (2, 3, 1, sure, why not, let's keep to the metaphor) are like Avengers MCU films -- they're the ones where the big stuff that's been hinted at culminates into a variety of climax. The non-numbered ones are like the rest of the MCU: varying degrees of semi-functional contained stories that nevertheless provide essential additional context, characterization, and development of the overarching narrative.
The comparison isn't meant to be 1:1, because KH and MCU have different approaches, but they're in a similar ballpark when it comes to the vibe and narrative climax.
- - - Updated - - -
Spoiler: