Yes I am not a big fan of the card system either. And that's not because I don't like playing it, but more because I see everyone skipping this game because of it. That's a design flaw to have people watching cutscenes on youtube rather than playing a game. This need to be addressed at some point.
For days, I am not sure. The game has been known to be repetitive with the missions and all and it wouldn't fit well on a console I think. A shorter version of it could be more impactful and more epic. But then, how do you develop the friendship between the trio without showing their day to day life? Days is a tricky one for sure.
But I am convinced that with full remakes, the entire dark seeker saga could fit on 5 games rather than 10 if smaller entries are fused properly.
What in the world?
How is CoM's gameplay a design flaw? It was made that way for HANDHELD play. Nothing about CoM's core mechanics should be a "flaw" because that is what the game was made to be! People should be damn happy that they can look at actual cutscenes on YouTube and not have to read text boxes from crap video recordings off a GBA screen.
Also, from what I remember CoM was VERY popular back in the day on the GBA. If anything, the PS2 version (and subsequent ones) are the unpopular ones. I personally prefer the GBA version than the PS2 version because the game itself doesn't translate well to PS2. The DISNEY worlds are empty and lifeless, there's no hub world or back tracking (that's fun), the main world (Castle Oblivion) is also empty and lifeless.
On top of all of that, the whole premise of CoM was that the cards in Castle Oblivion were being used to control Sora. It was actually pretty cool to see that control over Sora extended into his fighting. It was like a constant reminder that you weren't free, but rather trapped and under the Organization's influence. If there's anything they need to fix, is maybe make it easier to find certain cards to open doors. I think that was a design flaw because it was randomized instead of certain ways to guarantee getting the card you need to open a door to progress. The combat isn't the issue.
Anyway, I think IF they attempt to remake the Dark Seeker saga, they can blend things together and create something that's entirely new. It will require a lot of thought put into it because there will have to be really good pacing and structure. I think they could actually make it into 3 games: Re:Kingdom Hearts 1, 2, and 3.
Re:Kingdom Hearts 1: BbS (Ven's story), KH1 and CoM
Re:Kingdom Hearts 2: BbS (Terra's story), Days, KH2, and coded
Re:Kingdom Hearts 3: BbS (Aqua's story), 0.2, 3D, and KH3