Actually this pattern is preventing the freedom of expression.
You have not defined what you mean by "freedom of expression", but I believe it can be covered adequately according to three general possible meanings.
If you mean "freedom from consequences for asking questions", then consider that such freedom would run counter to one of the core principles of how SE runs: that good questions be voted up and bad questions be voted down is exactly how it should be. Keep in mind that "bad" on Meta also includes feature requests with which people disagree. As much as some of us may not like that feature requests are treated in this way, this is the custom of Meta. I'll note here that the question you linked to in this question has gone through multiple edits, some of which were actually suggesting a method to calculate ban lengths. Undoubtedly some people downvoted on this basis, even if they did not object to other parts of the question.
If what you mean by "freedom of expression" the legal notion of free speech, then the response here is that I do not know of any law that compels a private entity like Stack Exchange to provide a platform for people to express themselves.
If what you mean by "freedom of expression" is the idea that it is healthy for SE sites to allow users to express their opinions about the governance of the sites, then SE is doing an excellent job. Consider that it is possible for any user to come on Meta and post a question or post an answer.
Now, one of the reasons there are bans in place is that people who repeatedly ask bad questions are a drain on the system. Resource are limited, and people who take the time reading and dealing with bad questions could be spending their time doing something for the site. Which leads me to this:
Actually downvotes doesn't show or require any effort, and the huge amount of them proves an emotional behaviour.
I've seen very little evidence of emotional behavior in voting. I've gotten some downvotes that I believe (but cannot prove) were due to someone being pissed at having their question closed, but they were rare. And regarding effort, as I've mentioned above resources are limited. Most likely, when someone downvotes a post and does not put some effort towards improving this post, the choice is not between improving this post and doing nothing, but between improving this post and doing something else useful for the SE sites. The time spent improving a bad post can be spent answering a question, or editing a post which has some flaws but is closer to perfection, or any number of other tasks. In other words, the effort is not lacking; it is just spent elsewhere.
The way to avoid a negative outcome here is the same as anywhere on the internet, before posting, the user should spend time lurking and learning the customs of the site. This is important anywhere but even more so on SE sites because posts are voted on and such votes carry potentially substantial consequences, and even more on Meta due to its peculiarities.
And let me add this, because I've not been active on Meta that long so this is still fresh for me: I've seen some suggestions being heavily downvoted on Meta that were suggestions that crossed my mind early on. I could have been the one asking these questions and getting slammed. But instead of asking right away, I lurked and realized how Meta is different, and then I spent a good deal of time looking at old questions.