You might also get flooded with rather demanding emails by technically incompetent people who complain that your free source code release didn't solve their problem.

This. Happens so frequently, that making things OSS now carries an additional burden. I personally find it very painful to e.g. ignore the PR or issue opened by some hapless person in a bad situation trying to figure out the most dumbest thing. It makes the alternative (never OSS'ing anything) sound better, if only for my own peace of mind.