Because you picked the angry Au Ra face ;)
No, but seriously, it's annoying we can't keep up facial animations for more than a few seconds. I can understand that they say they don't want people to run around constantly with a scared face or whatever, but at least the most basic smile/indifferent/angry faces should be possible. Maybe also like a "stance" the way idle pose is where you decide which expression your character has, and as soon as you stand still or sit down, a few seconds later you'll assume your pose and facial expression.
