The common package is required for all SDK modules. You can see in the docs (comments for each dependency) that all the modules are optional to allow you use only those that you want. Eg. to add the map module to your application you need to have both common and map dependencies.
// required for all modules
// required if you want to use map view
Thank you for your comment, we've just updated the documentation (the Installation section) to make it more clear.