I beg to disagree. I've been waitlisted until the last minute (both for award tickets, and tickets in certain buckets) when it is evident that the flight would never be fully loaded. This would appear to cause loss of goodwill for little commercial benefit.

I have also waitlisted for an upgrade only to cancel once the deadline for online meal order has passed, and then to be OP-UPed anyway. This represents a loss of miles to EVA and, paradoxically, no goodwill benefit either.

Of course I don't have the facts and figures to hand - that is just my impression.