I don't remember Balrog's ending in SF4 but I'm assuming he's blonde there too?
Both Ed and Kolin are carried over designs from previous games, so all Capcom can do is balance it out with new characters who aren't blonde.
It's why there are no blondes among the genuinely new characters, Fang, Necalli, Laura and Rashid.
He was blonde in SF4 Balrogs Ending