Giving refunds isn't sufficient.
The reason why trades happen is that both sides value what the other party has more. So I value a book more than I value the money the seller wants to charge for it, so I buy it.
So that means that I would lose out with a unilateral unwinding of the trade.
Imagine the outcry if this happened in the financial world: "Yeah, we sold you that stock, but we're taking it back now, you'll be OK because we're giving you the money back." Isn't going to fly.
GP wrote DRM is morally evil, not Microsoft. That MS is giving refunds is nice of them, but doesn't invalidate the problems with DRM in general.
This type of hyperbole makes it hard to take anti-DRM arguments seriously. “It’s a less desirable technology choice” feels more like the right level of angst IMO.