Its been ever-present in American culture/journalism/entertainment pretty much since the beginning. Its also an expression of our freedom to do so as opposed to the many countries where such a thing is forbidden. While I don't always find it entertaining or in good taste I'm generally not opposed. With notable exception though, because personally:
I agree 100%.The only thing I think is disgusting however and crosses the line of expressing one's opinion and goes into the realm of shit trash, is when one depicts the execution of our President. Such a thing was also done to Obama when images of him were shown which showed a dummy being hung. Absolutely crossed the line.