I was thinking that myself. More that a combination of "new generation" context and appearances in their classic primes would provide the kind of dynamism and fluidity, as well as some unintentional world building, that some C- and D-listers could benefit from.
Even among the B-, C-, and D-list, DC has characters they tend to gravitate to and use. And even though a big chunk of the line would be taken up with the major franchises, it's safe to assume there'd be a lot of team titles and mini's so DC could cover as much ground as possible across the generations. And to show off the world building and development of the DCU across the decades (and to maintain consistency), you gotta touch base with characters as they age.
We likely could have seen, let's say Black Lightning, in his prime in a gen 2 Outsiders book; young, married, with a baby daughter at home. But it's not terribly unlikely that he'd also show up in a gen 4 book as well; older, divorced, with two superhero daughters. Maybe his kids replace him in a gen 4 Outsiders title or something, or who knows what, but either way you'd be looking at the spread of the man's life, his journey and the changes he went through. I don't think it's unreasonable to say that some fans who never cared for him before would see that evolution and be intrigued. And if two writers are building the Lightning mythos from two different ends, well they gotta communicate so the continuity stays straight even if one of them is writing the kids, which means some things get shared and utilized by both, and suddenly the mythos is growing.
Instead of the C-list being pushed even further into the margins, DC might have, quite by accident, actually given them the kind of growth and development they need. DC might have woken up one morning to realize that they had unintentionally built a fantastic and interesting framework around characters they had thought relegated to team ensembles and guest appearances.
Who knows if it would have worked out that way, of course. And even if this had happened with some characters, it wouldn't have happened with all of them and the guys like Vibe, that DC always ignores and marginalizes, they'd still be screwed over.....but DC's favorite secondary heroes......it might have (again, accidentally) worked out pretty well for them. Possibly.