I personally will never understand why people recast and have them imitate the old VA when the old VA is perfectly viable. It makes sense if you try to get a sound-a-like when the old VA has passed or has aged out of the role in the case of many, many kid voice actors.
I understand you could argue some scenes could take place between/before battles like Vanitas against Ven and Aqua; Terranort vs. Lingering Will; Kairi and Axel vs. Xion and Saix, but what throws a wrench into this is RAX vs. Saix. I could just be overthinking.
Considering how the mobile games never experienced the Keyblade War sequence like Browser X, I wouldn't be surprised if it was a repackaging of that. It was a pretty good sequence if Everglow's play through it any indication.
Really, the Disney characters need the biggest overhaul.
In the original KH game, the Disney Villains were actively driving the plot by carving worlds in search of their princesses and commanding the Heartless to do their bidding.
From KHII and arguably CoM, they are more filler.
My problem is really just how passive the engagement is. In the original KH, we have Maleficent and her council messing with worlds and gathering princesses only to be revealed to be the pawn of the Heartless themselves. The Disney characters felt like they had some stake in their own story...