@comicfanforever: Sorry but isn't any logic in your example. Just because Goku trained for "7 years" doesn't mean his SSJ3 is auto superior. Gohan had a short training session and was stronger than everyone. Half Sayians can draw out power easier and quicker than full saiyans. This was stated a few times.
Goku was clearing soiling his pants at the thought of fighting Super Buu, while Gotenks on the other hand, managed to fight decently against him. That speaks for itself.
Also, Goku pointed out pre ROSAT SSJ Gotenks was already going to be stronger than him.