Place a mineral deposit box (like the ones that used to be in the arcade) in the core.
This would give people a reason to go to the core, and it would give use to the two useless minerals.
I assume it would be simple to implement, they already have the mechanics of the deposit station worked out and everything.
They might even spice it up with the ability to get other stuff from the station instead of crowns when depositing a lot of minerals, like fire crystals or orbs for big deposits.
It would be a nice reward for people who have managed to unlock the core and can consistently make it there, because currently it's pretty anticlimactic and there's no reason to go there other than the achievement.
:)
The ores are explicitly used in the Arcade though. Multiple bits reference the energy traveling through the entire world to get to the core.
One alternative option would be changing that supply delivery mission. Have the players actually deliver those crates to the core. Deliver boxes, receive token. Use token to obtain Prestige. Or whatever.