Existence of objective good and evil takes away from the setting being serious in my eyes, makes it more goofy, cartoony.
If you had to choose, which game seems more goofy and cartoony? BG2 -- with its focus on alignment or DOS2 which doesn't have an alignment system? My answer is DOS by a mile.
I think DnD lives in some place on a continuum between the cartoony world of DOS1 and the realpolitik of Westeros. I love the Ice and Fire novels but I want to play an RPG in Faerun.