Something about Kingdom Hearts III always bothered me and I think your article really resonates with my own feelings. The original Kingdom Hearts featured a brash and naive Sora; while he's grown, he's still largely childish, and so is the plot of his game.

I don't have high hopes for Square to make Kingdom Hearts more mature and serious considering they're under Disney's watchful eye, but the secret ending for Kingdom Hearts III featuring Yozora does seem to take on a darker tone. Let's hope the next mainline title follows!