I agree 100% with you.
I think the problem isn't being all-ages, or the costume. I think the problem is the stories don't inspire or engage, they just sort of exist pleasantly on a very shallow level, while Babs as Batgirl and Oracle is capable of so much more. I always ask this of fans of Burnside, and I still haven't quite been able to understand - what is iconic or meaningful about the Burnside run (including Larson's)? What villains, conflicts, or character development has occurred that will stick with Babs?