[mschuster91]

Single sign-on. It's really nice to NOT have to copy-paste usernames and passwords from password managers into native apps but use a simple "sign in with FB/Twitter" and it's done. 1 second with a decent internet connection vs 60+s for switching to Keepass, entering the wallet password, actually finding the password, copying the username, switching back to $app, pasting the username, switching back to Keepass, hope it didn't for some reason decide to randomly lock, copy the password, switch back to $app, hope it didn't forget the username in the meantime...

edit: it becomes a special annoyance when an app decides to lock you out after n days (n usually = 30). Great from a security POV but hell is that annoying if it happens to multiple apps at once on a day. Or when you have 20+ apps with unique logins when you reset your phone... as login credentials/tokens are (rightfully) not cloud synced. Android desperately needs a password-autocomplete API, secured by e.g. the fingerprint sensor found on new-ish Samsung devices.