This is a rather incredible take, and you seem to be seriously arguing that Microsoft thinks customers are just giving them too much money and they just feel so guilty about it.
Microsoft once saw MPNs as necessary to get the sale. Now they don't, and they'd rather just cut MPNs out and make the sales themselves (more for them), and begrudgingly let it continue to exist in a minimal fashion.
I haven't done a ton of procurement in Microsoft-land but I have often heard the MPN described as a convoluted mechanism for offering software discounts through third-parties. As a Microsoft customer, I would rather they just have bulk licensing discount and easy-to-understand licensing one-click licensing rather than having to call (with a telephone!) up some third-party "distributor" to get a discount.
Microsoft once saw MPNs as necessary to get the sale. Now they don't, and they'd rather just cut MPNs out and make the sales themselves (more for them), and begrudgingly let it continue to exist in a minimal fashion.