What makes a revisit to the watchmen world so bad, but the idea of revisiting a world like marvelmans a good one? what series should be held to a higher regard, and why?
Because Gaiman's Marvelman was never finished. It was also meant to be a serialized monthly comic. From Anglo's original to Moore's run and then Gaiman's incomplete one, it was never billed as a mini series.
I don't think there's anything wrong with trying to revisit Watchmen really except everything about the Watchmen characters and the world were meant and written to be used for one story. The sole purpose of every character and situation was to serve the story. You can't really add to much to mythology of Watchmen. The characters are more reflections of themes and ideas (cold ward nuclear proliferation, impotence, nihilism, etc) that are supposed to clash with each other to make a really interesting narrative. The characters weren't meant to stand alone. I suppose they can be written to become that way though.
Another thing about revisiting Watchmen as a franchise is that Watchmen is as much an exploration of the medium as anything. To be in the spirit of Watchmen, I think, that as a creator, you would have to try to push the boundaries of comic book narrative. In my opinion, we have the spiritual successor of Watchmen in We3.
To be honest, I think it's boring to throw such talents at Watchmen in hope of making good comics out of it. Imagine if they had done this like eight years ago and thrown BKV and Guerra out of it. Instead of getting Y the Last Man, we get Watchmen sequels. Which one do you think is a truer successor to Watchmen?