To begin discussing free speech, lets make sure to clearly define what free speech is and what it's not. Wikipedia's definition of free speech is a good place to start:

"Freedom of speech is a principle that supports the freedom of an individual or a community to articulate their opinions and ideas without fear of retaliation, censorship, or legal sanction. The term "freedom of expression" is sometimes used synonymously but includes any act of seeking, receiving, and imparting information or ideas, regardless of the medium used."

Free speech does not include a "call to action", which is often examplified as: "Yelling fire in a crowded theater when there is no fire." It also does not mean that someone isn't responsible for what they say.

Free speech is important for a number of reasons, it is the basis of a free society and the moment you start limiting freedom of speech you head down the path of dictatorship.  No country anywhere in the world has succesfully limited speech without also oppressing its people and favoriting a certain group.

Restricting speech via law is a slippery slope, who gets to make the laws? Who gets to decide what's OK and what's not? Who defines which group of people are allowed to be offended and which group are not?

It is true that words can be offensive, but nobody is forcing you to listen to or read them.

When we listen to other people with different opinions, different points of view, it can open up our mind and show us a different way of seeing the world, that possibility is limited or illiminated when we start to limit freedom of speech. And that will hurt our society far deeper.