To be honest it's mainly for security reasons on our side. If someone breaches our servers, we can link it to a verified account and take action where necessary. In terms of social, when you log in you might have selected the box to receive emails from Themer about new updates and very important events. In this way, people who have uninstalled Themer because of some reason, might find that it now includes something that they've always wanted. Therefore it helps introduce 'new' users and in turn the more users we have the greater chance we have to generate resources (through the sponsored apps in the Smart Categories, which can also be turned off if the user desires).