You stole part of my idea, except you left out the part where every subsequent Super Saiyan transformation are the result of a very powerful Saiyan adapting to not having a tail, as stated by Raditz, then Vegeta a Saiyan's 'True power and fighting potential' is unlocked through their tail. That's why in order to 'Ascend' they must have the appropriate power, have strong emotional motivations, and be able to access their Oozaru transformation without losing control. So in theory, 'Super Saiyan 4' IS literally the ONLY Super Saiyan transformation, this is why every golden-haied form has weaknesses to balance out the strengths, whereas 'Super Saiyan 4' seems to be 'all pluses, no minuses'.

DragonBall IS one of the 'Big 3', the other 2 are Pokémon and Sailor Moon. Naruto copied alot of DragonBall's ideas, One Piece is still in the same genre, but is more like Pokémon, and Bleach is the result of DragonBall mixed with Sailor Moon.