Look at it this way, when Obama was in power he could have introduced laws which restricted free speech in the name of hate speech. Maybe he bans a few words and phrases no one like and life goes on. But then 8 years later his term is up and he hands over to Donald Trump. Now Obama is no longer deciding who can say what, Trump is. Do you think he would have used this power well?

What is and isn't offensive isn't fact, it's opinion. What some people see as a funny joke others see as hate speech and you shouldn't make laws based on opinions, they need to be based on facts.