I certainly agree with several of your arguments and points. I myself am a big fan of the "customer loyalty" ideal. I'm as loyal a customer as any company can ever hope to have in that I become so fully immersed that it becomes something I am passionate about and would argue for, this translates to comics, sports, or even mundane products. So from that perspective I completely agree that DC, as well as Marvel (not to pick on one of the big two), have become less intent on pleasing their loyal fans and more intent on bringing new customers and markets into the fold to improve their bottom line. This, unfortunately, is the inevitability of big business. Marvel's recent move of changing Thor into a woman and DC's changes to Alan Scott and Wally West are prime examples of trying to create "shock" amongst the general population in hopes of drawing in a more diverse range of fans to buy their product. Unfortunately straight, white, and male doesn't sell like it used to. That's not to say that I'm a racist and believe all heroes need to be straight, white, and male because I'm very much a fan of female and minority characters as well (Justice League was a fantastic foundation for me to grow attached to Wonder Woman, Hawkgirl, and Jon Stewart as my Green Lantern when I was a kid). In the end this alienates those that have bought their comics for years and are long term supporters of their work and creations. There is almost a certain sense among the top that they can spare a few die hard fans since most will buy the product regardless, and they want to pull in new subscribers to bolster sales overall.
The obvious difference in material between New 52 and Pre New 52 is certainly there. The characters are different, the direction is different, and the feel is different. From your own posts it seems that a lot of it is less than positive for you (I certainly am not intending to put words in your mouth), and I can understand that. Pre New 52 had a lot less of a "needs to be darker" feel to it (at least that's my personal opinion) and the characters were a lot "simpler". The characters weren't just super-powered, but stood for something and represented a core of ideals. Superman could be counted on the be the boy-scout. Batman was always the anti-hero; the hero that Gotham deserved, but didn't necessarily need or want. Wonder Woman was a heroic and strong image for women and so on. The stories were built on decades of genius writing and legacy from the Golden Age, Silver Age, and Bronze Age as well as their trials through the modern age of comics. But despite all of this I do think there has been some positive direction from the New 52 era. I believe that the characters have a new opportunity to grow and really become the heroes we loved in Pre New 52, but we are now taking part in that journey. Aquaman has regained a sense of legitimacy as well as popularity, which is far better than his seemingly endless reign as either the King of Atlantis that talked to fish or brooded with a hook for an arm and in dire need of a haircut. I personally like how Wonder Woman's origin is being done and the explanation for her powers, and I think it's a fantastic step in the way of feminism (I prefer the term equality) that Diana is a demigod amongst the likes Hercules and Perseus.
In the end, however, I think the New 52's greatest strength is still the accessibility for anyone. Collecting comics can certainly be a daunting task even for an avid fan. Jumping into a constant time stream that has been ongoing (more or less) for 50, 60, 70+ years is downright intimidating. The reboot does appeal to new fans, or even old fans who want to start on a new character and be able to start with an origin or easily established start point. Do the stories necessarily make the same impression as some of the greats of the past? No. I've yet to read a storyline that does rival some of the most inspiring like you listed. With that being said, however, I'm willing to give the creative minds at work time to get into their groove. We may be 30+ issues in with most titles but we're in a current fad as well. The 80's and 90's were a wreck more or less for comics, yet some of the greatest story arcs ever did come out of the bloodbath of violence and grit that comics were back then. I think we're also in a bit of a hump for creative direction, we seem to be recycling a lot of veteran writers across titles and expecting them to perform at their best every time. Like any free agent in sports, writers and artists need to be in the right situation to flourish. Putting a great player on a bad team or in a disagreeable game plan rarely works out. Furthermore we, as fans, are attaching a stigma against DC and Marvel as much as DC and Marvel are attaching to themselves. We are angry at the big two for having a dozen Bat titles and a half-dozen Supes titles and forty Wolverine/X-Men titles, but they're still making bank out of beating that horse which is far from dead. We want "edginess" despite you and I looking for inspiration instead. Creativity and fresh ideas are looking towards the more indie companies for that very reason. Who wants to be attached to The Avengers, Batman, Superman, Wolverine, etc. when you're at the mercy of Marvel or DC and their structured plan? The answer is less and less people. Superheroes will always be popular in comics, but the Walking Dead and similar stories are gaining ground because they allow for greater freedom of ideas and art that aren't set within a rigid precast model.
With all that being said, what would you suggest to improve the New 52, or what would you have done instead had you been in DC or Marvel's situation? I'm not being argumentative, I'm simply curious. I myself can't think of too many other ideas. As much as I'd like creativity and fresh outlooks to be brought in, the characters must still remain the same. Superman, for example, can only ever be the golden standard for goodness, morality, and courage. This severely limits how much can change regardless of new origins or new villains. The stories can only go in one direction which scares people away from writing or drawing these characters. It's a fine line, and reboots/retcons are the popular choice because it's an easy reset button. Some fans get angry, some leave, most are either ambivalent or neutral, and some love it. But that's how it always goes and in ten years when they feel things have stagnated too much and they need to bring in some new talent it'll happen again, and we'll bemoan the changes again.
But what would you do? Because as much as I'd not like to see reboots it's hard for me to come up with a way to visualize a plan that simultaneously appeases your loyal fans, brings in new fans, and helps your bottom line. Maybe you have some ideas I haven't thought of myself?
When I said we're in a current fad and moved on to mention the 80s and 90s I was generally referring to the idea that we are again (and maybe even still) in the popular trend that had begun with the darker anti-hero movement that brought the likes of Blade and Spawn into the world. The Death and Return of Superman was itself an argument against this "grittiness" and need for comics to be darker and bloodier, and argument for the good old days of morality, respect, bravery, and being a "class act" and that was over 20 years ago now.