On the topics of promotion and the OGN format instead of floppies:
I do think there would be some benefit to additional promotion for the lower tier books but I think the gains there are going to be incremental at best. I would argue that there is a significant chunk of readers that only want to read "important" books/characters and making something "important" involves either 1) getting big name talent on the book or 2) making the characters central to universe wide event - probably a combination of a two. Even doing that though isn't a guarantee of continued success though, take GL once Johns left for example, readership went downhill pretty fast. Now that's not to say that I think DC is doing everything correctly, I do think for example they could stand to utilize their female characters better.
In terms of the OGN format, yes the the OGN/bookstore market is huge right now but it's primarily in the young readers market, not traditional superheros. DC tried to break into that with their young readers stuff but outside of a few hits (Garcia/Piccolo's Raven for example) it hasn't been as successful as they had hoped and I have a hard time believing that more normal superhero works would capture that audience. Additionally any sustained push for mainline OGNs at the expense of floppies is going to piss off the direct market since the latter is their lifeblood and in general an OGN is probably going to feel more disconnected from the floppy line which once again gets us into whether a book is "important" or not.