>ITT: Theories you've come up with to rationalize odd design quirks/mistakes
I have a theory that GF initially wanted to make the Platinum Regis available from the get-go, but they weren't satisfied with the job they did, so they just crammed it into a one-time event and forgot about it. The result you see in the final game is a touched-up beta room, which is why you hear the generic Snowpoint Temple theme and a weird shitty MIDI version of the Regi Theme.