I think with how things have ultimately turned out, Vixen and Black Lightning would have been much better choices in the long run.I think there's a number of reasons they decided to "promote" Vic. He's "toyetic" yes (great word) I think that played into it, but he also offers a powerset the League doesn't have (Batman's gadgets notwithstanding), decades of history and a fair amount of larger media appearances, and he's a non-legacy character. John Stewart would've made more sense yes, but he shares the GL mantle with several characters, and Hal casts a big shadow. A lot of other PoC heroes are in a similar situation; they either lack the history and uniqueness to make them appealing as "core League" or they're tied to other (usually white) heroes (like Steel).
Really, I think if DC was going to pick a black character to put into the League who really offers something unique to the group and can stand as a solo IP, your options are basically Vic, Black Lightning, and Vixen. All of them offer something to the League beyond diversity, all of them have decades as team players, etc. But DC had beef with Isabella and Vixen doesn't have quite as deep a history as Cyborg does. I think now, after Metal and everything, DC has started to see something in Mr. Terrific that goes beyond the Batman-style "tech-based, stoic guy" archetype but back in 2011 he was too close to Bruce in terms of what he offered.
Vic *could* be a great League member....but DC hasn't given us that yet. And he definitely needs his Titans history back. He doesn't need to be a founder of the League, I actually think he offers more as a Titan who moved up. We need that "90's Wally West/Kyle Rayner" perspective and as a highly experienced hero working on a new team, *the* team, Vic would be a great fit.....if only DC put in some effort.