I'm not an active points buyer. I have a stash at the moment which I'm working out how to best to use. I've not considered buying under this offer (or not) yet.
People do value points bookings though due to their flexibilty to cancel at realativly short notice to the arrival day as well as cancel and rebook should the rate fall.
Neither of those apply to the lower cash rates. And not everyone has a corporate or partner rate which in effect turns a cheap non cancelable rate into a cancelable one.
And I think a lot of people earn status via stays than by qualifying points. I wouldn't have made diamond the last few years on points alone (even after factoring in the 'lost' points not earned when using points to book)