I listen to old school metal mainly because I think it's the best representation of how metal should be. Completely inspired, ready to push limits and play music even when you may not be the best at your insturment. Also it simply just sounds better to me. Like old school death metal, the gritty sound and muffled production only makes the music meaner and more fierce to the ears. However modern production is suitable if used to give off a particular atmosphere.
I like the spirit of the old. I think it could occur in any age, but is rare in this age.
Like in literature, there are greats throughout the centuries, but their mentalities are similar: they focus on the art itself as a means to saying something about life.
The writers that suck, on the other hand, are imitating others and have a lot of aesthetic (form) but very little germinal material (artistic content).
The term "old school" when used to describe an attitude apparently confuses people if this thread is anything to go by. A cutting edge band like Crimson Massacre is as "old school" in this sense as anything from the late eighties.