If you want to consider your online writing as a business then you should indeed include using Google Analytics in your business plan.
Although it is not necessary to earn money, paying attention to the information Google provides will help you avoid being clueless as to why you are earning money or not.
The various analytics reports give you a heads-up on which of your hubs are working and why, as well as which are failing and why.
Of course you will need to educate yourself with how to read the reports and get the useful information out of them. There are a lot of helpful hubs people have written to guide you.