It's the same problem a lot of people had with the Kenshin dub/sub. Kenshin comes off a lot more feminine in the original Japanese track, being voiced by a woman.

For me, DBZ Goku just always had this very assertive, manly voice, and hearing him sound that young is just very very strange. If this was original Dragonball, I doubt I'd have a problem at all. It's just the context.