Originally Posted by sparkkirby

I think it is just because they couldnt get a good blond color on the snes. Here is a good response to the question that i saw when i searched for it to see if there was an official reason: "If I had to take a guess, I'd say it's because the SNES could only store so many colors on a single pallet. And they didnt want to waste game space on hair."

Note: the above is not the official reason it is a good guess though.