People who are angry enough to torpedo a project might not realize just how easy some software fixes can be, if the developer is told more about the problem. When users E-mail me about a problem, often I can fix it within hours (or even minutes!) once I know what to look for. A return address is also important because sometimes I have to ask follow-up questions; besides, when I’m done I always want to send a link to the fixed version.
I’ve done open-source for a long time. In the beginning I was outright shocked at how some people behaved, much like this article states: even though I had not received a single E-mail (to my clearly-published address at the time), I would dig up scathing reviews of my stuff on web sites back in the day. I used to be mad, and sometimes I wondered why I bothered to work on anything (much less give it away for free). Eventually though I decided that I needed to take all input — even the “angry anonymous coward” kind — and use it as fuel to improve whatever I could.