[ray_sun]

re: Apple Mail, it just depends on who you ask. If you prefer Gmail, then Facebook could have mimic'd Gmail UI instead. The point is that unifying the different transports doesn't solve a real user problem. It's not like people are having problems sending email or SMSes to each other today.

[pyre]

It doesn't solve a user problem per se, but it may make it more convenient to have a 'one stop shop' for managing all of those things.

Supermarkets carrying things other than groceries (e.g. lightbulbs) didn't necessarily solve a user problem (i.e. people just went to the hardware store for light bulbs), but that decision was still a win for supermarkets.