What I dislike are the implications it makes in terms of Mickey's keyblade now that Keyblades can magically break after all these installments in the series. It's clearly established Kingdom Key D is the safest way to travel to the RoD, if he can still use it to travel there after getting his keyblade broken by merging parts of it with another keyblade, why doesn't he break all the parts of it and give it to everyone?
Wouldn't it make sense that everyone has the power to travel to the RoD safely? Why keep that power to himself instead of giving it to Riku at the very least?
What's stopping them from destroying all the keyblades in the graveyard and forging their own broken powerful keyblade