No it's not required of course. Visual Styles Modules has been made to make it easier managing modules and styles.

All basic operations like arrange modules or assign custom styles such as colors, fonts, etc can be done using a visual environment with no coding required.

Of course if you are a more advanced user and you have some CSS coding skills, you can take advantage of the integrated CSS editor included in Visual Styles Modules. This allows you to edit CSS files of your template to get more advanced customizations.