Ohh that thing. Dont really think its needed for gameplay. The "ZOMFG transformations" people would than have to deal with a really downgraded form 3 just so that form 4 isnt overpowered.
Besides that wasnt actually a transformation. His cells just regenerated him into his perfect form because they had the memory of how he was built at that time. And his powerboost came from the Saiyans abilitys to get stronger when healing from near death (and he really was nearly dead that time).
I rest my case ^^