Do you have to? No.  *Should you?* Yes.

Why?

Because it's not about you.

When you work with people, they do get used to you and they get emotionally attached.  Giving people a chance to say goodbye is a kindness, it is also a good business/career move.  You may or may not go back to that company, but if you do go back to work again, you may need references and you don't want to burn any bridges.

Just leaving without a word may offend certain people.  People you might not think even care could turn out to be your strongest allies in the future. As @Dank said below, leaving without a word could get the rumor mill started.  People tend to gossip, and they will fill in with fiction where they don't know fact. 

If you want to avoid too much fuss, tell people on your last day and let them know what a pleasure it was to work with them.

Before you leave, send a group email saying that you will miss everyone and enjoyed your time with them.  This will leave a fondness for you with your coworkers and it is the professional thing to do.