It allows the clever, the insightful, the vile, the distorted and the idiot equal time on the soapbox. It allows the despised the same opportunity as the beloved, it allows the retort. There's no obligation to listen, no obligation to say that which is acceptable. No obligation to make sense and no obligation to agree.
A vibrant, healthy democracy relies upon the noisy and obnoxious as much as it does the quiet and agreeable; without one, the other cannot exist. Without that vitality, that voluble debate, you have sterile obsequiousness. Without that ability to offend - you do not, cannot, have a free society.
Ya gotta love Freedom of Expression.