Mostly, yes, but I think at its core, the world benefits from honesty more than out right agreeable- or disagreeableness. We should speak up when we feel the need to agree or disagree, but we shouldn't play devil's advocate for the sake of it.

We absolutely should play devil's advocate. It is the attempt to think about a situation from a different angle and usually is understood to be such. Not an attack; a shake up to see if the structure stands to opposition.