Designed to hose token or reanimator strategies; incidentally breaks Commander. Wizards would do the former but not the latter; could this be printed?

You could get rid of the 'hoses commander' by just requesting the card be cast, and not care about the hand. That would also allow players to use suspend creatures and Haakon, Stromgald Scourge... but, for the most part, it would do what you want.

Or say "From hand or command zone", you've already paid the rarity cost, so you're allowed to use words :)

"Cast out the uncast caste!"

I wanted it to also prevent your opponent from casting things from exile or the graveyard. Referencing the command zone seems like a bad idea outside of a Commander precon deck.

If this hoses Commander quite this badly, you're right that it wouldn't get printed.