This is an internally flawed argument in my eyes. Your need for a downvote functionality is offset by someone else's need to not have it.
When taken to absurd extremes it becomes clearer. Suppose you demanded the right to imprison people, because of a deep need to express yourself in such a way, and swore that your neighbourhood would thank you for your decisions. And reasoned that since you're a responsible person, you would never abuse it so others can trust you. Also you hope that since everyone will be granted equal rights, other people will not go off the rails imprisoning everyone.

I think the flaw with the "stifled feelings" here is this: if the playing field is even (as it is with Steem - everyone is subject to the same set of rules), there can be no talk of censorship per se. No one is really getting censored. It's more a hindrance of a missing and perhaps very valuable functionality.

Having said all that, I totally agree with you that Steemit would benefit from a proper downvote option, simply because negative feedback is productive, awakening and valuable. Of course it can be abused, but so can the positive one.
It needs to be figured out well and tested first, but I'm pretty sure that in the long run, it would strengthen the community, filter out a lot of garbage and add to the value and perception of Steem.

So all in all, I agree with the conclusion of your post, but not exactly with the reasoning you provided.