So it seems that Facebook is now rolling out the removal of Messages from the main app. I can now no longer respond to messages in the main app and was forced to download Messenger in order to remove the notifications in the main app. It doesn't seem to be forced on everyone in the US though as my boyfriend can still open and respond to messages in his main app. Both up-to-date iPhone 5's. It's like when they roll out changes to news feed or your profile. Anyway, this isn't proving to be any better than messaging in the main app. Still confused as to why they made this change.