I think this may be a problem, but I think it's more anecdotal than anything. When I was in college, I never felt my tuition was a quid pro quo agreement that I'd get good grades. My grade depended solely on my own hard work and dedication to learning the subject. I wanted challenging classes.
As a free market libertarian, I think this is probably a positive thing. A lot of these professors are raising a stink because for so long they've been isolated from public criticism of their performance. The truth hurts sometimes, and it takes public criticism, not student evaluations that the professor can throw in the trash, to get better performance.
In my former music career, it always upset me to see a bad review published about a project I was associated with. But I can honestly say that after I put my emotions aside, the critique was usually instructive. Maybe these professors should get off their arrogant high horse and take an honest look at what their students are trying to tell them.
That's fine, since you knew who your critic was (the review had a byline). What would you think if someone anonymously dissed your music on posters attached to telephone poles and bulletin boards around town?
If there is criticism of me that could potentially wreck my career, I am certain that I would want to face my accuser (or at least be able to respond directly to them).