Well being of a generation who never had the pre-Marvel Age to compare to, I think I can see the difference better.

That said, JB, are you sure that Stan "accidentally opened the door for a similar way of thinking about the characters"? Having recently read those early Spider-Man stories again, and seeing Stan's continuous use of for instance "Spidey" on covers, in the kind of writer-to-reader captions often used, as well as within the stories themselves (including Spider-Man's way of relating to himself), it seems to me as if he rather consciously tried to open that particular door. To really make the readers connect with their heroes rather than looking at the godlike beings from afar.
For me as someone not present from before what you perceive as an erosion of certain awe values, those very personal aspects of being able to in a way "befriend" and "imagine oneself in their place" always seemed very important elements, and most likely why I've tended to prefer Marvel over DC.

And to use your analogy, if I could ever meet some of these heroes I would most likely talk to them as well-known friends, although awed by their powers and uncanny feats. But their is an element of knowing someone like Peter Parker fairly well after reading as little as the first 20 issues of Amazing Spider-Man (and I have read more by far).

As I've said before, one of the key elements in the success of the Marvel Age--the personalization Stan and his people brought to the table--has, unfortunately, contributed to the mess the genre/industry is in now.

This personalization made the reader feel like part of a special club (which led to the aggressively insular nature of LCSs and the like), involved in the creative process, and familiar enough with the characters to see them not as mythic demigods, but as "guys like us".

I just remember all those old Avengers issues where they were constantly taunting each other with Shell Head, Cap, Shield-slinger and the like.

I guess most fans saw that as superheroes having an informal atmostphere amongst themselves.

As I've said before, one of the key elements in the success of the Marvel Age--the personalization Stan and his people brought to the table--has, unfortunately, contributed to the mess the genre/industry is in now.

Sorry, I don't agree, and not just disagreeing to hear my head rattle. I don't think Stan Lee's personalized style hurt the industry at all, I think it helped build it. The mess that is the industry today, which is really just a bloody hangover from the mess that was the industry in the 90s, was caused by a lot of bad editorial and publishing decisions, but I don't think editorial irreverence had anything to do with it.

Here's my theory.

The primary reason the superhero genre/industry got into a mess (in the 90s) was the Art. Skilled veterans with a great personal style, like our friend Mr. Byrne, were not part of the problem. A hundred soulless artists who drew comics based on aping Jim Lee and Todd McFarlane were the problem. Many had very little foundation in basic skills. Many are still being published today. Many have trouble making deadlines. All these things are interrelated. But before that, there was the boredom factor. If you eat vanilla ice cream every day, you are going to get tired of it. The comic-buying public did, at a time when comic books were facing huge competition from videogames and PC games with dazzling new graphics. 

Secondary problem: After decades of being underpriced, comics suddenly became overpriced in a cooling market. They should have done everything possible to keep the price at or below $1.00 an issue.

Greg Kirkman wrote:
"I said it was one factor that led to today's situation, but not the only one."

Fair enough, Greg.
I just wonder how much of a factor it actually is at all, given that it to me would seem to work contrary to what it's building up.
Personally, I think I treat people I know well and care for with more respect and care than those that I don't. Even though I certainly hope that that doesn't mean I'm a disrespectful jerk to everyone else, I similarly would say that I treat genres and media I care a little bit extra about with a wee bit more respect as well. So I'm not entirely sure I am buying the notion that familiarising the audience with the character on the level Stan achieved would play a big part in this degradation.
But heck, I may be an abberation in the human race in this respect and my point thereby nullified. Who am I to know, right?

Following Kevin's argument a bit, I'd actually offer the "rock star" syndrome as a bigger culprit. People in it for the glory of the glory itself are probably less likely to care about the characters in question. The fact that the investment wave must also at least have seemed to carry whispering promises of money probably didn't help either.
And as always a large chunk of the blame lands at the door step of editors (and EIC especially) for allowing certain trends not to only gain a foothold but more or less overrun the market.

Key word, there, is "taunting". These were (mostly) manly men kinda rolling around taking mild pokes at each other -- pokes that were given and received on the understanding that each had reach pretty much the same level. They were not used, except disrepectfully, by those who were of a lower level. In fact, who here remembers the issue of NOVA in which our young hero met Thor and called him "sir"? If only that had caught on with the fanboys. If only the insistance had been on respect for the characters, not the kind of embarassed, affected ennui that infects too much of the audience today.

The difference of course being, Chris that we don't follow Officer Jones's adventures on a monthly basis, with entry points into his inner thoughts and dreams. If I had the same insight into Officer Jones I hav with say Spider-Man, I'd probably call him Jonesy.
Now, would I respect him any less? I'd probably respect him even more, since people of good character is worthy of respect.

As to the so-called fan mentality which supposedly causes writers to feel so close to characters that the feel free to change them into whatever... I'd argue that they do not feel very close and friendly as they do not respect the character as is. They are basically the same kind of "friends" who just tells people to change their lives to fit their own. Is that a friend? Is that respect for someone one knows? Methinks not.