Thunderbolt is Sony/Apple competitior to the original USB. It is higher performing with I/O bound to the host vs in the peripherals of the original USB design. It was more expensive so USB won but due to its superior bandwidth and processing it is used for ilink/thunderbolt video cameras, vga dongles, and ethernet.
You sound like you're describing Firewire (developed by Apple, Sony, and a number of others), not Thunberbolt (developed primarily by Intel).
Thunderbolt comes with MS Surface and any Apple product to connect vga, ethernet, dvd, HDMI, video cameras, and other dongles. Mac users use them too. USB 2?? Well it can't handle these well or at all.
This paragraph confuses me, what are you talking about when you say USB can handle these well or at all? Dongles are almost always used on the USB port.
An easier explanation is that Thunderbolt is a functional, external PCIe bandwidth connection. I see it far more often in Pro Audio and Pro Video than any other purpose as its high bandwidth allows better access. It's still a young tech (2011) as opposed to USB (1996) and Firewire (1994), so there's plenty of things that still can come from it.