They were banned before 2008, when the South Africans convinced FIFA that it was "necessary" for the whole experience.
Go ahead and tell that to the Scottish, who have been banned from bringing bagpipes to their qualifiers.
While you're at it, let me know how many times you heard the Argentinian drums, the English songs, a USA chant, or anything from, I don't know, any other ****ing culture on the planet. I bet you BZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZzzz.
They've effectively let those stupid horns kill half the reason to watch the world cup, to see and hear how all the different fans act, so we can pretend that the games are occuring in beehives.
Next time it's in America, we'll just play canned pop music the entire match over the stadium speakers, since it's an integral part of our "culture". I'm sure everyone will be fine with that.