Didn't Google have messaging figured out with Google Talk? Everyone was on Gmail all day (as many still are) and people actually used it. Then they let it wither, came out with Hangouts, and it's been a downhill train wreck from there. Google Talk had the potential of being one of the biggest messengers in the world...they own Gmail and Android (!!!!!). Are you kidding me? There's really no good reason for them NOT t…
Not everyone is on Gmail. There a untold millions of users who aren't interested in creating a Gmail account. Those users will never be reached with any "just use your Gmail account" strategy.