The horns really annoy me too, and I agree with everything you said about safety and fan behavior. But there's no denying that bee-swarm hum is part of the South African football experience. It may be a recent phenomenon, but it's a point of pride for their fans and part of their identity. Right or wrong, native Africans see it as their stamp on post-apartheid Association Football.
The comparison to hooligans isn't fair. There's no intent to hurt people or ruin the game for others, even if that's the outcome. Hooligans brutally assault innocent people without provocation, destroy property, throw body fluids, and threaten/humiliate players and officials. Even worse, it's not just out of control drunks, their actions are often organized and planned.