Way too many haters.
First off I didn't know there were so many people that didn't like AaAaAA!!. I don't care for the game's humor but the gameplay is rock solid. I've had a ton of fun with it. And Super Meat Boy, Bit Trip Beat, and Amnesia's pedigrees are all well established.
I played Defense Grid for about 90 minutes last night and loved it, too.
Toki Tori is the only other game in the pack I've played, but I also found it to be quite pleasant.
TL;DR: There's a good sale on an indie game pack and Portal two is going to be unlocked a day or two early. So where in the heck does the hate come from? Most ARGs don't even have a proper ending, and there is no precedent for Steam voluntarily unlocking pre-loaded games early.
The funniest thing about the hate is if Portal 2 just launched Tuesday as normal, everyone would be happy. But give gamers the opportunity for early access, and suddenly they become entitled whiners.