Uh....
Wally was not only the main Flash of the DCAU, but they pretty much pretended Barry never existed. Furthermore, Wally was a founding member of the cartoon Young Justice team alongside Dick Grayson, when in reality, they didn't really have to be. Are you going to tell me that it would have been that hard to simply have Bart and Tim in those roles (you know, the way it was in the comics) when they didn't even use the original Aqualad? Plus, I assume Wally is likely to see a return in season 3 of Young Justice given that the voice actor
did tease that Judas Contract clip they showed as a "sample of more to come in YJ season 3."
As for his exposure in the comics, I have to say its really not any less than other characters get. Garth and Donna and Roy don't appear anywhere else regularly besides Titans either. Abnett has also confirmed that he
does have plans for Wally. Plus, we all know Wally
is going to play a big role in the larger Rebirth storyline. He and Superman are the only ones who seem to have memory of the timeline as it was before Flashpoint. And, assuming Reborn is about making people remember Superman's Pre-Flashpoint history (evidenced by Lana apparently forgetting Nuperman and NuLois in Superwoman #8 preview), he's probably going to be one of the principal actors
alongside Superman (one of the flagship characters of DC Comics).
I don't see DC straight up giving us Wally West with his memories of being on the League and being the Flash and not having
him be one of the main guys to see to it that those memories of his are restored to the timeline.