The advantages of SSJ2 were never taken advantage of to its fullest in the Buu Saga. The art style you used masterfully shows that "peak" that SSJ2 was in the Cell Games. After all, it seemed that Gohan had no real limit in terms of energy when fighting Cell. Even when he was injured by his superior form, Gohan still had enough strength to completely eradicate him from existence.
If Goku and Vegeta used their respective SSJ2 forms simultaneously against Fat Buu, there wouldn't be anything left of him to regenerate -w-