That is why the Macbook Air still works better for me than an rMB or rMBP. I know that my experience is not common or applicable to others.USB A to C dongle u can get for $6 or just buy a cable replacement for the same price.
Of course it would have been better if Apple had put in at least two ports or even kept an additional USBa port for a while. But buying a computer just because of this minor connection problem?
USBa won't come back to the other MacBook lineup. So u can buy now an adapter or in a few years.
And happy for you that all conference rooms in your life have mini display ports. I never saw one in many companies I was working with. Just hdmi or even vga. So dongle life also here...
I find it fascinating how there are some who are unable to comprehend how a device that they deem unacceptable for themselves is viewed as the best (relatively speaking) option for others.