Another impact of this crash is that I seem to have lost my saved games for this scenario - a war that I had put quite a few hours into, and maybe was going to win :( This affects the playability of the game more than the crash itself, and makes me think that the treatment of save games in Arma 3 needs to be a lot more stable than it is in its present state.

Regarding the problem of your save games disappearing after a crash.....

Refer to ticket T74993, "Saved games go missing", for a detailed explanation of this problem and a work around. That ticket was fixed and closed, but the issue still exists if ARMA 3 crashes as I found out the last few days and as you found out as well. The work around that worked for me was the comment by goertzenator on Sep 11 2014, 8:05 PM.

The problem boils down to the "Save and Exit" function. When you load ARMA 3 and resume a single player scenario, it deletes the "continue.Arma3Save" in your "Saved" folder (while you are playing the scenario). Normally, when you exit the scenario, you would click the "Save and Exit" button and it recreates the continue.Arma3Save file again. This file is just a save game file, like all your other save game files. If this file is missing, then you cannot resume your Scenario even though the save games are all still there.

This folder is found in two locations depending on which profile you are playing as:

Default Profile
C:\Users\(username)\Documents\Arma 3\Saved\steam\Scenario_Name.Map_Name

Alternate Profiles
C:\Users\(username)\Documents\Arma 3 - Other Profiles\(ARMA Profile Name)\Saved\steam\Scenario_Name.Map_Name

The work around is to copy your last save game file and rename it to "continue.ArmaSave", and then restart ARMA 3, you should now be able to Resume your scenario and access your previous saved games as well.

This work around has nothing to do with why ARMA 3 crashed on you. But the same result could happen if the power goes out, you hit the reset button, etc. Anything that quits ARMA 3 in an uncontrolled manner.