Agree with the view that it was DC's attempt to emulate Marvel's Ultimate Universe... recreating all their top properties in a modern perspective, without holding on to any dated ideas.
My faves were Superman and Wonder Woman, Batman and GL were ok, Titans probably my least favorite. IMO the problem with Titans was they were trying too hard to separate it from the ideas of sidekicks and a not-yet-formed Earth One JLA.
I think the biggest roadblocks at this point are that they've already done the big 3, meaning any future new OGNs would focus on characters that DON'T sell as well.
Second, as mentioned above, the publishing frequency is problematic for generating any interest. When the titles only come out every 6 mos. to a year...they completely fall off the radar.
I honestly never even noticed GL book two came out. Never thought to look for it.
If DC wanted to keep these properties going, and I'm not convinced they do, I think they'd need to increase the frequency and launch something big, like a JLA title that finally brings them together.
Could also be good material for a E0 JLA/E1 JLA crossover.