I'll wait for more feedback and then send another patch.
If you assume users read the descriptions before choosing a severity, I think you assume a lot. I suspect most users choose from the list of words, assigning their own meaning to them. So of course, every bug becomes a "blocker," because hey, it's blocking me getting my work done. Modding bugs down, and telling users to vote if they really care about a bug, is just part of triage.
--Juan