Any true "pro" uses a 17 inch screen anyways. I'm an auditor, and we're constantly moving our computers and external monitors, and we have 17 inch hp computers. We need the real estate. Nobody who is working on a laptop should be using anything less than 17 inches. Maybe Apple has realized this and is removing things like the Ethernet from the 13 & 15 inch models.
Been downvoted so much so probably heard it all, but I'll add to why this is such an ignorant comment:
I know someone who is a professional film editor, ie it's his job, he doesn't just pirate FCP and call himself a pro. He's one BAFTAs, RTS awards etc etc for his editing.
And guess what? A lot of it is done on a 15" screen. So no, not everyone needs 17" screens.