This is why I don't get the 1-port only idea.
It's what happens when you let an award-winning designer of phones and music players design a laptop: you're meant to charge it up at night and run off battery all day (Apple says it has "all day battery life" so if it ever runs down during the day, the world must be turning wrong.)
Seriously, this is a computer for people who live in the cloud and never use it anywhere where there isn't WiFi or give a presentation where there isn't an Apple TV already wired up to the projector. I'm sure there are plenty of people for whom this will work fine. For the rest of us - move on, nothing to see (yet).
Longer term - the ambition of USB-C seems to be one connector for everything, so in a perfect world you'll soon have generic USB-C displays that work like the Apple Thunderbolt Display but with one less wire, USB hubs that include video out, and any USB-C peripheral that has a mains connection will double as a charger for your computer.
Still, the MB would have been a better computer with a second USB-C port, and any future MBPro better have multiple USB-Cs. Although, as I noted above, it doesn't look like you can drive a 4K display
and USB3 peripherals at the same time until DisplayPort 1.3 comes out, so I'd still avoid this generation.
Meanwhile, the original MacBook Air only had one USB, the 2011 MBPs only had one Thunderbolt... what was that (alleged) Einstein quote about repeatedly doing the same thing and expecting a different result?