All products work in different ways - when we are in a command we use ESC to quit the command - so if the command also includes selecting objects, what would Esc do then?
TBC has a left Click menu that has a Clear Selection option which is I agree 2 clicks, ot it has the click in clear space to clear a selection which is one click, but if you have images or PDFs or Surfaces in view, then that will not always work (agreed), but the left click to clear the selection is not so hard (having said that I next to never use it ...), but many people of course will never even find that as a tool to use.
This is down to UI design and we appreciate that when you switch from one system to another that there are some things that are alien in the new system - hopefully you come to like the things that the TBC platform does that Civil 3D doesn't do, I am sure even Civil 3D has it's quirks and shortfalls.
We all strive to make the user experience better, and thanks for the input, the TBC product team watch the forum and they will likely take your comments into account for the future.
Alan