I agree the main selling point for 5-12 year old children is aesthetics. They will buy whatever they think looks coolest. The anime will also help drive the sales of Dark Bull, Wolf and Storm Pegasis. So the kids that you mention kouri are unlikely to purchase a circular Beyblade, that is not in the anime, and the newer version is not in the anime.
(brad can correct me if I'm wrong as he knows much more on the subject than I do)
(brad can correct me if I'm wrong as he knows much more on the subject than I do)