The commit message plays an important role in revision control systems. They are the first thing other people will see of your commit. Git and related tools work best when following a certain guideline for commit messages. A deeper [introduction on git revision log conventions][a-note-about-git-commit-messages] is helpful to understand the scope. Commit messages should describe what changed, and reference the issue number if the commit closes or is associated with a particular issue.
This leads to more readable messages that are easy to follow when looking through the project history. But also, often commit messages will be used to generate a change log for releases of an application, plugin or code base.
Having commit messages that follow this formatting will prepare your code for distribution, and make formatting consistent.