A straight-forward answer will be "Yes".
The reasons why you would require an unsubscribed button on your emails
Complying with GDPR Laws
One of the key reasons is that as per GDPR laws, there needs to be a clear and intuitive way through which a user can opt-out from your communications. That is easily made possible by an unsubscription button. If you run multiple lists, it might also help to have a preference center through which users can opt out of any or all lists at once.
To avoid being marked as spam
Another important factor is to avoid being marked as spam. There are harsh repercussions of being marked as spam by many people. The most popular email clients will simply start blacklisting your domain and move all your emails to spam. When people can’t unsubscribe from your emails, they simply would mark it as spam or move it to the junk folder.
Effectiveness for your campaigns
People who don’t want your emails will simply ignore them and if you don’t provide them an easy way to unsubscribe, they will either mark you as spam or keep ignoring, both of which are not the ideal scenario that a marketer wants. If you remove them from the list, the effectiveness of your campaigns might improve and you’ll receive an uptick in the key metrics as only people who are interested in the emails are getting it.
All of these reasons make for a strong case of adding an unsubscribe button in your emails.