TNG was a fine show. TOS was a fine show. But they were mostly different shows. I can see also why some TNG fans who never followed TOS at all could look at it and wonder why folks found it so great. Then some TOS fans get overly defensive protecting the product. Bar fights break out. Hair pulling. Eye gouging. Name calling. Slapping. It gets nasty.
And then some Klingon calls the Enterprise
a garbage scow . . .