:D I agree it's a shame it is so complicated. (I was not having problems with content going missing but NOW I have a new problem with this Launcher.)
Nothing goes missing in game because the DCCache TMP files are exact duplicates of the ones that are already present. I'm in the middle of a team build that is undergoing testing so I am starting my game several times a day. So, this has been tested a lot by me. My build partner is not having this problem.
If you just delete the TMP files and start the game with the Launcher, they will be recreated.
If you delete them and bypass the Launcher, they will not regenerate and you can be playing your game in a couple minutes.