Re: why didn't WD/HGST put a jumper in
So they can resell you a drive when you need that feature, or resell you a drive if you got the wrong part number by mistake? Drives that can be used in either configuration would be damaging to their sales.
Either way, double the number of stock line items, double the number of sales. That's how it works doesn't it? Having massive inventories of very specific drive/controller combinations in the supply chain obviously has some hidden benefit to them.