Goten appears in the last arc Dragon Ball Z to bring us great joy for your semelhança com Gokuwho had died in the battle against cell. Or it is easier to think that the similarity in the appearance between the two characters is strictly related to the fact of being pai e filho, but in reality it is that there is another more important reason.
It's just the simple fact of being a father and son, Akira Toriyama would make Gohan equal to the saiyan raised on Terra, but not the fez. The young warrior's year, a visual that always differs from his country, embodies in terms of powers he has something similar.
Apparently Goten's first episodes had quite an impact, because in addition to looking like Goku, his voice (except in Latin American dublage) was the same as Gohan and Goku when we were children.
Goten's characteristics are enormous power that he attains in all his power, easily turning into a Super Saiyan, all elements meticulously thought out by Akira Toriyama.
And obviously there is a quest of genes in the similarity between the two of you, or sensei Toriyama does not have that way because in his plans Goku would not return to Dragon Ball. Assim, Goten would keep his image alive with that similarity.
The protagonists who would fight to maintain peace on Terra would be Gohan as leader, along with Trunks and Goten.
Changes that will not occur in Dragon Ball
Foram changes that unfortunately do not occur 100% in Dragon Ball for a very simple reason: the oil of the public, in accordance with the reviews of the Sensacine. As people did not want to continue accompanying Akira Toriyama's work, Goku did not take part in the adventures of Warriors Z.
It was Toriyama's own that you take precautions and, when you have a chance, try to turn it over and never throw it away again.