Really, the title says it all. But I'm sure I can muster up a few paragraphs of a nice old fashioned rant. 
Time and time again I encounter near (and full) outrage from a person when they hear me spout the blasphemous phrase "I don't like Watchmen." Just the other day I had a friend say something like "I'm still completely at loss as to how you can not like Watchmen." But, I, as well, am completely at loss when people are shocked at my dislike of Watchmen and Alan Moore, in general. Sticking with Watchmen, since it's a nice easy target and perhaps Moore's most famous work, it seems to me to invoke what I'll call the "Citizen Kane Effect" in people. To quickly define the CKE, it's when a person conflates historical importance with "Greatness" in all areas. 
Now, had I been alive and sentient in 1941, Citizen Kane would have probably blown my mind. I could have potentially dubbed it the Greatest Film of All Time. Similarly, were I sentient and reading comics in 1986, Watchmen could very well have had the same effect in the realm of comics. However, I was a year old when Watchmen started being published and obviously less than a year old when Citizen Kane came out. And it wasn't until I was 16-18 that I started reading comics, so a nice 15 year buffer between me and Watchmen. 
Now, historically, I'll assume Watchmen ushered in the modern era of comics. Gritty, dark, fucked up stories. And Citizen Kane ushered in a new era of film making. Innovation, experimentation, and courage. These are great and to be respected. But being the first on the scene doesn't make you the best on the scene. Watchmen may have changed comics, but in doing so it made it easier to be dethroned from it's position of "Greatest" (if it ever was or if there is such a thing as "greatest"). And to make things clear, I love the themes in Watchmen: mental illness, moral ambiguity, etc. But, it bores the shit out of me.  Moore accomplished all of this and more, in my opinion, in a lot less pages in The Killing Joke - the only thing of Moore's I love. 
Now, on a recent-ish post by another comicvine user, it seemed to be suggested that some rather popular ("overrated") authors who openly cite Moore as influence, owe him quite a lot and that it may be difficult to discern where these authors begin and Alan Moore ends - or to put it another way: They're just regurgitating Alan Moore. However, if I understood the argument correctly, I definitely disagree. Let's use Neil Gaiman as the example - and I won't hide my bias, Neil Gaiman is my favorite author in the medium of comics as well as other forms of literature. Now, Gaiman has definitely been influenced by Moore. Gaiman has been influenced by Lord Dunsany as well. And probably Snorri Sturluson as well, but to be safe I'll just say Norse mythology in general. And a million other things. However, to say that Gaiman is regurgitating (regurgitating is my word, not used by any other poster, by the way) Moore, Dunsany, Sturluson, Homer, etc...would be, to me, a very odd opinion and one difficult to demonstrate. There's a key difference in simple copying and using an idea or a character and making it your own and Gaiman, to stay with my example, has always - in my opinion once again - fallen into the latter camp. Even with Stardust, a straight up homage to Lord Dunsany, it's very much a Gaiman story. 
Perhaps one day my opinion of Alan Moore will change. But for now, Alan Moore stands in my book as the most overrated author in the comic book industry. 
And remember kids! Don't fall prey to the CKE! Historical importance is just that and does not imply anything beyond it! The French Nouvelle Vogue made better films than early Hollywood did. Certain New Hollywood films made better films than certain Nouvelle Vogue films. And certain modern films are better than New Hollywood film. Each movement inspired the next and artist build upon the works of their influences, not simply reproduce it.