I appreciate the educational piece offered here. I do understand. It does not change my view, however.
Dongle away.
Thing is, I rarely do. I'm either on the go (at a coffee shop, hotel, business meeting, etc.) and I connect NOTHING. I have my laptop, trackpad, keyboard, built in display, and wifi or cellular tethering.
At my desk at the office or at my home I plug into a single dock the gives me my external keyboard, mouse, display, and Ethernet. What used to be USB has long since transitioned to network (printers, scanners, external storage, etc.). This is not a new thing.
That is 99.9% of my use. I have a few adapters for odds an ends—TB Ethernet for when I either need a second Ethernet connection or network troubleshooting outside of my home or office, TB FireWire which is used almost exclusively for working on older Macs in Target Disk Mode (pre-Thunderbolt), my serial adapter, and various video adapters that I've had since 2008 when Apple transitioned to Mini DisplayPort.
It sounds like a lot but they mostly sit in my bag. And I appreciate the fact that I can have two Ethernet ports on my MBP and even my Mini. Thunderbolt means I get native speed and the ports I need, not those that have been predetermined, not some crappy USB to Ethernet connection.
I understand the convenience factor for some people but I am so tired of people telling me what constitutes a "Pro" laptop. Flexibility is king in my opinion and Thunderbolt maximizes that. TB3/USB-C is even better because it's being adopted beyond Apple (thank goodness).