In order to add an ActiveSync account, the mail server must support at least version 14 of the ActiveSync protocol. Gmail only supports version 12. Note that even though Gmail might eventually upgrade to version 14 or later of the ActiveSync protocol, they could still end up blocking Outlook in favor of their IMAP and Google Apps solutions.
In fact, Google actually dropped EAS support for new devices for free accounts on 30 January 2013. EAS is only still supported for (paid) Google Apps for Business, Government and Educations users.
