Failure to communicate the why
"Just do it." An excellent slogan, but not an excellent management approach. There's a concept called democratic centralism. The idea is that you argue a point until a decision is made. But once the decision is taken, you all work your hardest to get it done. The underlying concept here is that people are aware of the reason for the decision, even if they don't necessarily agree.
I've gotten very good at fighting for ideas I don't agree with. (I give the credit to my 20-plus years in the ad biz.) But it's much harder to do if you don't understand the why. We all know that compromise is the engine of progress. You focus on the good and live to fight another day. But you can't focus on the good if you don't know what it is. It's the spoonful of sugar that helps the medicine go down. Perhaps not in a delightful way, but it's what it takes to get the -- oh, whatever (I've taken all this metaphoring far enough).