It's very simple. When you presale a device that has an anticipated hash rate you're required to forecast what you can get for it based on the where it stands in the network at the time of delivery. If you overestimate it's value when setting it's selling price you end up with pissed off customers who overpaid. If you take the more respectable route as Bitmain does selling when you can actually deliver then more network hashing equates to less profit for your product as you can't expect to get the same return from it. To discount a sizeable amount of hashing power is just foolish no matter if the flavor of that ASIC doesn't suit your pallet.