Does Business Platinum have the same competitive environment as the personal card? Prices (and discounts) reflect supply and demand, nothing else. If other issuers do not have a competitive product, American Express has little incentive to discount. If Business Platinum does not provide good value, just cancel.
I've eyed the Consumer benefits for a long time but I've been trying to avoid the hit on my credit report to close this and open something new instead - you can't convert one to the other. But that time may finally have arrived.