I have CiviCRM 4.7.22 and WordPress 4.8.2. I don't get the WYSIWYG CKEditor for a New Mailing or the description in a new event. Both are present on the CiviCRM sandbox site.
From the documentation I think that it should be installed with WordPress and set as default. Permissions can't be an issue as I am an admin.
While WYSIWYG editor disappeared in CiviCRM 4.7.16 looks similar, the answers seem to relate to Drupal not WordPress and nothing suggested there helps.