The other problem is that "objective goodness" renders a lot of moral arguments absolutely pointless. What is good? We can point to an angel of "objective goodness," ask, and we know. There is no moral quandary to be found. Good is what denizens of this plane say is good, and it must be good because it's a plane of objective goodness.
This is similar to what drove me away from using alignment back in my AD&D days. It felt too easy to solve complex moral problems with a "Know Alignment" or "Detect Evil" spell. I usually include plenty of Obvious Evil in my games, but I want the majority of people and monsters to feel like folks in the real world... striving to survive, making deals, making mistakes, building up trust over time, etc. As GM, I certainly don't want the job of measuring all of them against some sort of objective in-game standard. Much more fun to simply let them do their thing and see what happens.