Livre d'Or

I think it is important but I don't think it's intrinsically important. To put it bluntly: there is no point communicating honestly and frankly 100% of the time if what you're communicating isn't something that your SO/friend/family member actually approves of and likes. I could be completely frank about my need for personal space and my SO could be completely frank about why he thinks my need for personal space is daft but however honestly we communicated, it wouldn't change the fact that we disagreed.* Or, to put it in a different way: communication (on some level, not everything needs to be communicated as others have pointed out) is necessary but it's not sufficient.

*Hypothetical example.