Depends on your workflow, of course. But for me: absolutely a non-issue.
The rMB is the best laptop I ever owned, period.
Exactly. I've owned Macbook Pros and currently have a Macbook Air. I plug something in maybe once or twice per month... and it's usually a USB backup drive. The only other thing I can think of is maybe a Ethernet adapter for travel (but I don't even use that much anymore).