This relates to most things that people have posted here, sorry I picked your post mate, it was just easily accessible.
Most masterpieces are grounded in their influence on their respective medium and on world culture as a whole. Whether it is for better or worse, any piece that has altered the landscape is, as if by default, considered a masterpiece. I'm not saying this is in agreement or not, just stating a fact.
When it comes to Watchmen, it was one of the first attempts to create a "serious" or "gritty", comic book with traditional superhero-like figures. (Yes, Watchmen is a comic, that's how it was originally presented. The "Graphic Novel" was a compilation of 12 separate issues.) Most of the material we talk about on The Escapist would not exist if Watchmen didn't attempt to alter the landscape of pulp-fiction-esque material (video games included) from camp to grim.
It just seems as if most peoples' claims are short-sighted. While some works of art may not stack up to ones that follow, they may have seriously influenced the art to be produced in the future. Is Mozart's music as good as Gustav Mahler's? I don't think so, but that doesn't make Mozart shittier than Mahler. Mozart shaped the landscape of music forever. Without him, there would be no Mahler to speak of.
To use a more familiar example, I've gotten the impression that most people on The Escapist enjoy prog-rock or some variety of metal music, and lots of them tend to bash the Beatles. I'm not saying that they can't have an opinion of their own, but, seriously, without the Beatles, we wouldn't have any of the rock music that followed them. They essentially invented the concept of the rock band. I think we need to at least respect that if nothing else.