Having the ability to completely create a website into a Social Media one. I think that most people here want DM's Live Video, Check-marks, and other social media related things. Why not just completely implement all social media features that other websites have. Group messages, Private messages, Home feeds from people you follow, having an app in the mobile store, activity dots, Facebook like UI and other things. I strongly believe that this would completely change the game for WIX and all of the users.
EMOJIS AS WELL!