IMHO, allowing payment by USD/credit card kind of defeats the purpose of everything we're doing here.

How so? Someone would be paying USD to mine coins, effectively exchanging USD into cryptocurrency. Nothing wrong with that.
It defeats the whole purpose of Irreversible Bitcoin Transactions. You rent a rig with a credit card, start a chargeback, say that your card was stolen and used for some shady services. BAM. Providers lose everything.