Thing is, being open / honest sometimes triggers emotion and does not stimulate discussion or progress.
My experience (source: being Dutch / Swiss-German) is that it really really matters not only what is being said or even how true it is, a very important aspect is what / how the receiver interprets the message. When I am with my Dutch (Amsterdammer) family and friends, we are direct in a very specific way about specific subjects. Being with my Swiss-German family and friends we are too: but on different subjects and in different wording.
Just like humor translates lousy, so do nuance and social etiquettes.