The ability to tell jokes should never come under arrest. One should be able to joke about anything they wish, regardless of who might get offended. They way I see it is this:
A comedian is kind of like a musician. The audience is like a stringed musical instrument. Some sounds come out louder and more clear when the strings have some tension.
To abandon the tension in all of the strings, for fear that someone will get offended, the result would be a poor-sounding song. The comedy would be lost. The art would die.
This is why comedy has to constantly push boundaries – to keep tension in those strings. To keep the art alive. To discover new sounds. And most importantly, to make sure those sounds exist for future generations.