Ability to customize users's roles on the fly

Hi, Recently custom roles was introduced. While this is a great functionality to manage workspace and admin permissions it still doesn't offer flexibility to assign permissions on the fly. When i am adding a user I need to be able to select from the menu items from account, billing, customization and workspace settings.

Right now we have to create a custom role every-time such a need arises. This is especially difficult especially when we have several admins adding users on the tool. It's difficult to keep on top of all the permissions that come with a specific roles.