Let me back up for a moment and respond to Captain Kal's defense of fans turned pro.
I didn't mean to suggest that things immediately went into the crapper once this crowd showed up, but I do think that what we saw over time was a shift from stories crafted in the traditional mold to ones that are more self-referential, more derivative and less accessible.
This is true, incidentally, of movies and TV as well. When these media started out, creators came from all walks of life with all sorts of interesting personal histories; they had been through Depressions, wars, etc. Most of them dreamed of being the next Ernest Hemingway or Norman Rockwell. They invented comics; the pacing, the layouts, the story structures, but beyond that they also brought their life experiences and knowledge of things outside the world of comics. They had one foot in the real world and given half a chance, they'd have bolted from comics to find their fortunes in that real world.
Over time, a new generation of creators grew up; their experiences, on the whole, were more limited, more insular. The youths of the late 40s and early 50s were the first to have popular entertainment geared directly to them, the first to enjoy the mass marketing of toys and licensed characters, the first to have American culture devoted to prolonging their childhood instead of being encourage to grow up quick and start supporting the family. They were bombarded with cartoons, kid's shows and comic books and those influences shaped their imaginations and united them in a common, shared mythology.
By the time these guys and gals grew up, they had definite ideas of how their favorite characters should act, what they should do and what they wished they'd done but for whatever reason never had. And once they got the reigns, they made those things happen. They weren't frustrated novelists and would-be magazine illustrators "slumming" with comics work; they were people who grew up with a comics job as their goal. Same with movies and TV; the people making them now grew up on them and their lives have been focused on getting to Hollywood. They know everything about lighting and editing and scoring, and they sure know the formula for big box office. But do they really have any stories to tell? In my experience, usually not.
Here's an example for you. Read this 10-page Batman story from 1954 (
http://batman.superman.nu/bat-comics/divermystery/) and see how many facts are crammed in, how many visual references to real-world architecture, how many plausible (if unlikely) dangers and escapes. Then tell me the last time you saw any of that in modern comics. A 40s or 50s Batman comic was about solving a crime; a modern one is about Batman butting heads with Robin, or Nightwing, or Superman or whoever. Modern heroes are totally focused on intrigues and frictions among their little cast of characters and whenever they do get around to facing some threat, it's probably some villain with just as complex a back story, preferrably a former ally. Even now the "big event" in the back titles is the return of Jason Todd, a character who last figured in the comics 20 years ago. The 1954 story is accessible to anyone who can read; a modern comic requires a degree in Pop Culture history to decipher.
Anyway, I guess my point is that while there are certainly a lot of talented fans turned pros out there, the net result over the decades has been to create a medium that is self-absorbed and unwelcoming to new readers. The first generation of fan-creators got to do things with the icons that had never been done. By now they are expected to do whatever new crazy thing the shifting winds says is "kewl." Today's fan is tomorrow's writer or artist, so the publishers pretty much let fan opinion, or their perception of fan tastes, take precedence over things like fidelity to a character's core values or any sense of continuity of theme. (Is Batman a hero or a nutjob? Well, what do the Wizard polls say we should have him be this month?)