Yeah, I dig old Scooby-Doo (pre-Scrappy) just fine. Yes, it's formulaic as fuck, and yes, putting a laugh track on a goddamn cartoon ranks in the top ten worst ideas in the history of Scooby-Doo, but it's a fun show that found its niche and captured its zeitgeist -- which isn't as easy to do as it looks (as pointed out in the episode of the current series where Scooby teams up with all the also-ran Hanna-Barbera Four Kids and a Mascot Mystery-Solver Teams).
Plus if you want to look for any philosophical underpinnings, it's a pleasingly subversive bit of humanist propaganda -- there's no such thing as ghosts, the villains are always adults who lie to children, and the skeptic solves the mystery while her friends are unable to overcome their fear and think rationally. (
Sims expounded on this at some length.)
And yeah, I think it's perfectly reasonable to say that Mystery Inc improves on the original in nearly every way, but it's also the apotheosis of forty years' worth of nostalgia, navel-gazing, and cultural analysis. Plus a shitload of great examples of What Not to Do.