I think just like the old ECW (according to some people anyhow, I didn't watch or like the old ECW), people tend to only remember the good things about the Attitude Era because the good by far outweighed the bad. I agree with most of what's been brought up.
It had colorful personalities and larger-than-life characters like Austin, Rock, Triple H, Mick Foley, Undertaker, DX, etc. Also, as far as "pushing the boundaries" go, no one had ever had edgy content like that before in wrestling. ECW did, but it had a very small audience overall. WWF was doing it on a much more mainstream platform. The whole novelty aspect (in my opinion) of seeing these sort of boundaries pushed on a wrestling program is what made it attractive. That's why "bringing back the Attitude Era" today wouldn't automatically work or fix anything.
12 title changes in one year (they also had exactly 12 IC Title changes in 1999, I believe) is ridiculous but that was part of Vince Russo's whole belief of titles just being props and thus having no real value. Titles still felt important otherwise at least.
I didn't mind Austin being a superman character and I think the difference between Austin and Cena is that it didn't go on nearly as long for Austin because his career was cut short because of injury. We saw him throughout '98 and '99 and the last part of '00 and all throughout '01 and the first part of '02 and that was it. And he was a heel throughout almost all of 2001 so that doesn't count. He wasn't booked as a superman per se in 2002 so that doesn't count. So that's a very short time frame for when Austin would seem "invincible" at times. It's been going on a lot longer for John Cena and it's beyond stale now.
Gimmick matches were also more special back then. The Hell In A Cell, for example, was new back then. But now? It's been done so many times that it's lost a lot of it's impact. Same goes for the Elimination Chamber match.
When most people say they wish it was like the AE again, they usually don't mean they want the Shock TV aspects back, but they want the color personalities and larger-than-life characters back. AE did that better (IMO) than any other era in wrestling. You just need believable characters who can act and have charisma and are good on the mic and can have a believable feud and match and it will attract people and you can do that in PG. That's pretty much the basis of selling tickets and PPV in wrestling - take two guys, put them into a believable conflict (title, personal hatred, etc.) and make people want to see the eventual match and payoff on PPV.