I use a MacPro driving 3 27' displays and also have a few portables as well. It's just a matter of synching info. I can't imagine having to deal with hooking up a portable.
Plugging my 2013 Air into my desk when I come home isn't a big hassle - I plug in the speaker cable, the power cable, the video cable, and the USB hub. It takes me ten seconds[1] to do unless one of the cables falls; they're normally sitting right where I put the Mac. It sits on a lower shelf and runs closed; there's a Bluetooth keyboard and a Wacom tablet on my desk. (I'm an artist.)
It'd be nice to have the single connector I guess. Once I got an adapter[2] and plugged everything into that I'd save all of, I dunno, five seconds?
I'm also not driving three displays. I have never liked multiple displays. They don't work well with a Wacom tablet, and I go crazy from constantly seeing slight color differences; when I'm at a cafe, I use the laptop screen; when I'm at home, I use the external monitor.
Now you have one person's explanation of why she schleps around a single laptop that she also uses for her desktop.
1: Literally; I just timed it. 6.6s to leisurely unplug it, 10.3s to casually reconnect it.
2: http://store.apple.com/us/product/MJ1K2AM/A/usb-c-digital-av...
Synchronizing is hard. That's the problem.
I want to close my laptop after a day at the office and be able to continue working on the train or an airplane, immediately, if I need to.
This isn't easy to do without having a single machine.
I'd seriously consider an iMac if Apple would solve b.