If I may play Devil's Advocate for a moment:
I'm not sure a full-line, hard reset would be a good idea, despite its many good points.
For one, as evidenced by
The Legion of Super-Heroes and its many re-boots, it's hard not to revisit some storylines and "update" them. While I thought the post-
Zero Hour Legion did a good job of this, others were upset that certain things like the Suneater, the Fatal Five, the team fighting Mordru, the team taking on Darkseid, etc. had all been done before. And when they broke away with that, such as when they killed Leviathan (aka Colossal Boy), they freaked out.
Another thing is that it would have made introducing these 52 titles and characters a nightmare. The
Ultimate line is an example of how to do it right, since it started with one title (
Ultimate Spider-Man, then introduced
Ultimate X-Men, both of which introduced ideas, concepts, and characters that lead to
The Ultimates, then they lauched
Ultimate Fantastic Four over the course of years). A hard-reboot of the entire line would be a nightmare to avoid 52 concepts all appearing at once.
Finally, there's throwing the baby out with the bathwater. In the case of
Batman and
Green Lantern, why bother doing a hard reset when you have top selling books and recent, popular storylines? Then there are the other titles, such as
Aquaman which benefit from being able to pick and choose what did and did not happen. Now most of the titles don't seem to be taking advantage of that, but some titles are. It's nothing new, as the post-
Crisis DCU did the same thing. Grant Morrison has even taken advantage of that by saying that all of Batman's history was in-continuity prior to
Flashpoint, it's just that some of the trippier stuff didn't happen as presented in the 50's and 60's, but was rather a hallucination of some kind. So, instead of reinventing the wheel and retelling the same story, the reader is asked to accept that the key parts happened, but happened differently than they remember. Thus,
Batgirl can still claim
The Killing Joke is in continuity, but it may have happened a little differently than Alan Moore and Brian Bolland presented it. I'm fine with that.
You could argue that the New-52 did not do a good job of this, and I would agree in some cases, but that still does not mean you had to dump everything. The condensed 5 year timeline, being an example of where it goes wrong. However, this is more a problem with execution than the idea itself.