Dragonball GT: Why were people against Son Gok�return to child form?
Most of the reasons have been mentioned, but possibly the biggest two are that he wasn't as serious when fighting and that he couldn't maintain his SS3 power. Most of the dislike comes not from Goku being a kid but instead from them using Pan, doing away with Gohan's mystic powers, the return to comedy, the use of a new creative consultant, and the new producers having basically just watched the DBZ movies instead of the series, which caused a lot of loop holes throughout.