What fraction of customers is affected by the issue?

That's always the first question I ask myself when I get a bug report. I can't fix every bug / annoyance. My software is already way more complex than I can handle, so I have to prioritize which bugs I fix. If the bug only occurs in a special setting and only happens for one customer that isn't important, then I probably won't fix it. I'll just say, sorry that my product doesn't work for you.

Now that customer will be annoyed, because my product was a good fit except for this one issue.

But if the product was open source, then they can fix the blocking issue themselves! I see this as a win/win situation.