Two were wrong because they aren't proprietary connectors, they are industry standard connectors. It has been more than a decade since Apple last sold a Mac with any proprietary connector. They only use industry standard ones.
FireWire operated at 400Mbps in 1994. USB 1.0 came out two years later, and was only capable of 1.5Mbps.
As far as I know, Apple was the first major PC manufacturer in the world to ship hardware with USB ports, but being hundreds of times slower than FireWire meant it simply could not compete.
Even today, FireWire is still faster than USB although the performance gap is much smaller now.
HDMI 1.2 and earlier have a maximum display resolution of 1920x1200,. Apple has been selling screens with higher resolution than that for more than ten years, but HDMI could not drive large displays until version 1.3 of the spec which still pretty rare among PC hardware today. That is why Apple never supported the HDMI standard.
MicroUSB only has five pins, and older iOS/iPods required 30 pins - there were no unnecessary pins on the 30 pin connector. Modern iOS devices have more powerful software and are able to send things (like video) digitally instead of over an analogue connection, so they only require 8 pins... but that's still to many to use a MicroUSB connector.
Thunderbolt is very similar to FireWire, it's essentially a newer version of the same thing. Where FireWire maxes out at 800Mbps, Thunderbolt currently does 10,000Mbps and is expected to hit 100,000Mbps in future (according to Intel that speed can be done now, but it's too expensive to be made available to the public).
They are more expensive because they do things that USB is not capable of doing.
Agreed. But there is no good alternative, either Apple needed to use proprietary connectors or produce inferior products with less features (eg, lower resolution screens that work with HDMI, video cameras that take hours to transfer short video clips over USB 1.0 instead of seconds with FireWire, iPods that don't have analogue video output cables to play video on your TV, etc)
But USB 3.1 changes all that, it increases the speed to be the same as Thunderbolt, more than 10x faster than FireWire, and it can drive high resolution displays the same as HDMI 1.3, and it can do 100 watts of power in both directions, and it's also dirt cheap when you're just plugging in a keyboard and don't need all of those features. USB 3.1 is the solution to a previously unsolved problem, and Apple looks to be the first company to ship hardware using it.
