You are welcome and I understand your disappointment. I suspect Canon tried to keep the cost low and the camera simple to operate.
Although leaving out an external mic jack might seem like a strange cost cutting measure, it pales in comparison to what the auto industry began doing in the 1980s effectively playing a game called, "what won't the consumer miss until after they purchase the car" and this is when conveniences like underhood lights went away. Even minor cost cuts directly impact the profit line and when multiplied across thousands of units sold of a popular model it does add up.
Many of Canon DSLR models do have a mic jack. Although less convenient, for highest quality you can use an external recorder with a built in mic mixer so that you aren't restricted to one mic and you can then sync the audio track with the video later. Having a friend stand in front of the camera and snap his fingers or do a single clap will provide an easily identifiable visual and audible sync point.
Depending upon what you are recording, you will probably want the microphone(s) to be in a very different location from the camera to provide the desired audio content and quality. You may find it useful to also record the audio on the built in mic to provide a sync reference throughout the video and the camera track can later be muted in your final edit OR serve as a backup in case something goes wrong with your external audio setup.
Rodger
EOS 1DX M3, 1DX M2, 1DX, 5DS R, M6 Mark II, 1D M2, EOS 650 (film), many lenses, XF400 video
