You kind of go in with the fannish assumption that the professional writer either wants to continue with the status quo or even understands it exists. 

And the truth of the matter is that people are often pretty awful at their jobs. The guy writing comics as his day job under a pen name in the hopes that his Great American Novel will allow him to quit his day job is the sort of guy you're going to be dealing with a fair bit of the time. If he really hates his job, he'll happily undermine it. 

And these are the kinds of people who exist within the pro ranks. Some of them just don't care. If they're boss came in with the stupidest idea known to man, they wouldn't argue, they'd just give him what he wants and be done with it. What happens if the boss doesn't care, what if he's the owner's idiot son-in-law who has been put in charge because he needs a career. 

What I see in this thread is people building up the Professional Writer to near mythical status, the guy who not only understands exactly what is essential to the characters he's working on, but steadfast in his loyalty to those ideals. 

The Starlog article linked up-thread kind of shows what writers have to deal with, so even if they want to do a good job, their bosses may be making that impossible because they want sensationalism, they want headlines, they want controversy over someone being beating to death with their own severed arm. 

These are your professionals. They're just as much a hive of scum and villainy as fans-turned-pro. 

And then there's the assumption that the fan-turned-pro who's writing Hawkman is a proper fan of Hawkman. To him, it might just be a gig to prove that he's capable of writing Green Lantern, so he starts writing the book like Green Lantern... which might end up being way more popular than Hawkman being written like Hawkman, so the bosses will say "keep doing that", because they're chasing sales. (Put him on Green Lantern, then he becomes a gibbering fanboy who brings back every obscure GL character he can lay hands on, because he's lack any critical thinking about what does and doesn't work in Green Lantern.)

Which isn't terribly different from pros deciding they don't particularly like the book they're doing and shifting it into something they do like doing and hope the boss doesn't notice and/or care, which has happened numerous times in the professional ranks. 

The fan-turned-pro just adds this self-referential sheen to the whole thing, which rarely does anything more than alienate potential new fans. They either care too much about the minutia or lack the critical eye necessary to work on their favorite characters. 

Or to put it another way... maybe Early Marvel was one of those rare and wonderful moments when a group of professionals came together who wanted to produce truly good work and were allowed to. Even then, it doesn't sound like it lasted more than about a decade. 

Correct me if I'm wrong, but didn't the aging of the kid sidekicks happen right around the time kid sidekicks went out of fashion. During the brief time I read a bit of Teen Titans, I got the sense that they really didn't know what to do with the characters after they had been cast off from the main books and aged them into something more in line with the current comic scene, namely the X-Men. 

If something doesn't work anymore, then only a fan will insist it stays as they remember. The pro is going to try to turn it into something that keeps the paychecks coming. 

Jack, while writers are certainly as human as the next person, capable of mistakes or letting a moment of fanboy squee leak into a piece, would you agree that it is better if they don't?

Well, certainly. I merely disagree about many of the examples as being fan mistakes. They're just common mistakes, which fan-pros also make... sometimes in a distinctly fannish way. 

But let's not put the Pro on a pedestal. They're often disinterested in the finished product and you can find many more examples of pros screwing something up royally. Cousin Oliver wasn't brought in by a rabid Brady Bunch fan.