One of the things I like most about the DCU is the idea of legacy characters. Yes, it leads to some really nasty continuity tangles and makes comic quirks (like character aging) really obvious, but I like the sense of history it provides. A superhero name, a costume, a power set, isn't necessarily something unique, but a mantle that can be passed from one character to the next, in a largely unbroken string potentially lasting up to the 853rd century. I enjoy that.
And I was exposed to it pretty early on. Some of the comics I read when I first started reading DC regularly were the Mike Parobeck JSA and the Jurgens JLA. The two issues of JSA I found featured both Wally West and Jay Garrick as "the Flash," neither of whom was the Barry Allen I knew from TV and my parents' comics, as well as Jesse Quick, who I recognized because I'd read about Johnny Quick before. There was even a guy called Green Lantern, who didn't look anything like the Green Lantern I knew. Over in JLA, there was another guy called Green Lantern, who still didn't look anything like the one I knew, but was clearly a different character. It wasn't confusing, it was intriguing: I think you hear this a lot from comics fans, but the minor characters, the legacies, the guest stars--as a kid, those are just tantalizing little glimpses at a fascinating universe with a fascinating history. It's why I loved the Official Handbook to the Marvel Universe and Who's Who as a kid, and I know I'm not the only one, but I wanted to know more about these amazing characters and what they could do.
If there's one lesson DC should have learned from comics like JSA and Flash--if there's one lesson that Geoff Johns should have learned but apparently hasn't--it's that no reasonable person gets confused by having multiple characters running around with the same name. And yet, for a company that prides itself on legacy characters with long histories, how many new-generation heroes have been sidelined or eliminated to make way for their previous counterparts? Recently, it's Firestorm, Hawkgirl, Flash, and Atom, but they're not the only ones. What about Green Arrow? Hourman? Dr. Fate? I can accept, for instance, that there's only one helmet and amulet for Fate, but what of the others? I can't say with any certainty that characters are being pushed to the sides or replaced because the higher-ups think readers aren't bright enough to understand that multiple people might operate under the same name, but I have a hard time thinking of any other reasons that this keeps happening.
I think the legacies offer a nice way to tell new stories, to expand supporting casts, to break out of ruts, and to prevent characters from being spread too thin or overexposed. And I think a lot of books understand this--Steel, Supergirl, and Superboy frequently show up as supporting characters in the Superman books; there was a time when both JLA and JLE had Green Lanterns, so Guy Gardner was on the former and Hal Jordan was on the latter; Flash frequently used the rest of the Flash family as a way to tell new stories, focusing on different Flashes or the relationships that tie them together. DC is a universe that should never run into the Wolverine problem, of one character appearing on six different teams--Barry can be the Flash of the JLA, Jay can lead the JSA, and Wally can be on the Titans or Outsiders or whatever.
Returning to the point, I think DC would be better off by fully embracing the legacies. Let some legacies be like families, working together as a cohesive cast; let others be like franchises, where different people operate in different places, so you can alternate between the focal characters and tell different stories, keeping everything fresh (specifically, I'd like to see a Firestorm book that bounced between Jason and Ronnie's different adventures); let other legacies be loose associations, joined by a Second Feature or something along those lines.
But for the love o' Pete, stop thinking that only one version of a character can have the spotlight at a time. This is a situation where you actually can please most of the people most of the time, why on Earth wouldn't you take it?