Google analytics and Webmaster tools are two great tools by Google which helps webmasters get insights about their website. However, they perform slightly different functions in how they gather and report data.
Google analytics is more about what happens in your website once visitors enter your website. Webmaster tools is mostly about the Google search engine and what happens before people click on your website link.
Hypothetically, If you have no intention of getting traffic from the Google search engine, you would have no need of Webmaster tools.