I think "mandatory" is a bit too strong, Dave. The first step is to learn how to use what you've got, and then start learning what else you might use to your advantage. I have several examples of nicely exposed shots taken with the Olympus camera, Olympus housing, and no external strobe.
Adjust the settings so that the flash always fires.
Set the camera to macro mode.
Look for subjects that will fill the frame when shot from a range of 24 inches down to 8 inches. Shoot in that range until you are confident with your results.
While in this learning stage, shoot in manual mode with a shutter speed of 1/125 and an aperture of f5.6.
Shoot and review. If your shot is over or under exposed, adjust the flash compensation and/or the aperture.
Here are some examples from a C-2000 and a C-3030


