Icons are the gateway to your application. It's what your users will interact with to access your app. To submit an application to the appropriate marketplace of your choice, it has to have an icon.
Because an icon is your app's brand, it's increasingly not enough to simply create a solid color shade and slap some text on it-users expect more.
There are so many ways you can procure an icon for your application. You could hire someone (either locally or online) to design one, or create one yourself using a plethora of applications.