Well, it's becoming increasingly clearer with all the revelations about their history that (a)most of the problems Green Lanterns fix have to do with things the Guardians brought about themselves, one way or another, and (b) that ultimately, the GLC is in fact the Guardians' bodyguard army. Because there's a lot of people who want revenge.
I mean, though it's pretty fucked up with him now, I do not disagree with Atrocitus. The Guardians' mistakes killed an entire space sector.(which makes it now Black Lantern-ready) Why should he not want the Smurfs dead? And consider the Guardians gave over an entire system, Vega, to crime, enslavement and greed as politics, as an exchange with Larfleeze. And ultimately they fear emotion because it challenges their power. But what does that power stand for? Protecting themselves. Consider the Final Crisis: did they do anything really to help or to fix it? The Corps did. But the Guardians did not. They just watched, and isolated Earth, making Darkseid's job actually easier.
One could be forgiven for thinking it would be better were the Guardians dead. All Krona did was cause the multiverse. They've done much more damage since. Their presumption in claiming they have responsibility for the universe because of Krona is very self-serving: would it not be more accurate that they presume the universe, therefore, is theirs?