As an aside: I always end up already owning the majority of games in these bundles, but I buy them anyway. Here's to hoping we can eventually register this one on Steam too.
Don't think they'd have much to lose from a 1 week pay-as-much-as-you-want deal.
Apologies for the poor explanation.
However, each of these games have been out for sufficiently long that having people name their price now is mainly extra frosting on top of an already well-decorated cake. It's a tiny bit of extra market penetration /after/ the game's already made an impact - along with some goodwill towards deserving charities.
I like it for the single point where all my games are, so I don't have to remember where I downloaded to, or where the keys are in my inbox, or even where I put install media. I just download the client, sign in, and all my games are right there.
It makes the DRM quite tolerable, and it supports indie developers, and it's ultimately the most convenient option for me.