I truly do not see it helping, especially as a first step. The vast majority of those bad and mediocre teachers that everyone wants fired? They're still around

I truly do not see it helping, especially as a first step. The vast majority of those bad and mediocre teachers that everyone wants fired? They're still around primarily because the school administration is comfortable with them. They don't complain, they don't cause problems, they don't garner parental complaints, they simply implement whatever new schemes administration comes up with to try to increase standardized test scores, etc. Removing tenure isn't going to make administrators magically start firing bad teachers that they like, even if standardized test results were a good measure of such. And your comment about parents with strong but ignorant opinions is spot on - one of the best teachers in my high school was fired directly as a result of parental complaints.