I feel like the inheritance ceremony took the fun out of the mystery behind the Keyblade. I liked it better when we all thought they came to people randomly.
I'm more concerned about these keyblade master ceremonies and training camps even started.
I would't call it training camp. This is more like how typical apprenticeships worked back in the day (and even now...). You seek out a master of the skill you want to know, become their apprentice to train in the art of whatever, then you are tested on your ability to do the thing and one day you become a master.
Apparently you can get a keyblade even without someone bestowing it upon you, even if you want to use it for war.
This has always been a thing. As long as your heart is strong enough, you can wield. If a Keyblade comes to you or not is a different matter entirely.
The inheritance ceremony only ensures that when the time comes (aka, when you prove the strength of your heart), you will definitely call upon a Keyblade.
The ceremony does kinda make sense for the overall plot though. There wasn't really any reason behind Riku being chosen for the keyblade and not just getting swallowed by darkness before that.
At the time of KH1/KH1FM, there really was no need to care about the why behind Riku being the chosen one. We were supposed to accept the fact that Riku, since he was a child, was able to see the keyhole on the door in the cave and that made him the chosen one. He was the brave one, the strong one, the one all of the kids looked up to and wanted to be. Whereas Sora was the not as brave, not as strong, and not as looked up to best friend of Riku's.
The game tries to show that Riku was special compared to Sora before the night of the storm, and Nomura has always been more about leaving things up to the imagination of fans. A mysterious weapon that chose Riku for a mysterious reason before it went to Riku. That was the something he wanted fans to think about.