During my day to day use, the only time I plug in to anything is when I sit at my desk, power, Thunderbolt and HDMI to get a glorious three display setup out of my MBPr.
That being said, when I am in meetings, or on the move for work, I don't carry dongles with me. Pure laptop for me. All of our meeting spaces have Airplay compatible projectors, so I sit down, make sure I am on wifi and connect to the display.
Transferring large files? We've got 1 Gbit to our desks, I can sling data from our Denver location to our St. Louis location at almost 300 Mbit/sec sustained. Also, wireless N/AC throughout the building.
In the world where you no longer NEED those ports, having a smaller lighter laptop makes all the difference. I already don't carry dongles with me, the new laptop with less ports wouldn't change that.