Fear Of Speaking One's Mind

I'm not sure why this is such a big fear.

I think generally the answer is that we, as people, get outraged quite easily, and so speaking unedited can result in outraging others.

Outrage seems to be there to trigger group  cohesion, i.e. if we're outraged at the same thing, we must be on a team and can trust one another more.

It still sucks that it is so hard to speak one's mind in a way that isn't intended to be malicious but can often be perceived as exactly that: with intent and hurtful.

Which is not to say that sometimes we are unintentionally hurtful and it is still our fault since we should have known better.  But I'm not talking about those times so much, as just the general ease of conversation possible between two people and the way we guard and select our thoughts to appease (at least I do this often) the other person more so than if we were speaking to someone else...