Ricky_Bobby: I'm pretty sure GOG is doing all it possibly can to get more AAA publishers on-board. We've had plenty of successes this year with games like Crysis, Mirror's Edge and Shadow Warior 2. It's not really up to GOG.
And it's also not enough for GOG to get more contemporary AAA titles, they have to convince Steam users to buy the games through GOG and not Steam, or a Steam-key vendor. There are two problems with this:
1) AAA games on GOG are generally more expensive (just my impression), Steam keys are much cheaper
2) they will need to open another gaming account, i.e. they won't have all their games in one place anymore
To grow it's business GOG is trying to take customers away from Steam-key vendors, but that is unlikely to happen en masse. However, where else is GOG supposed to generate new customers from ?!
More quantities of quality old games? Picking up abandonware titles and giving them a nice shine? PBEM services?