'It seems that this Dutch roll mode is poorly damped on most of the airplanes, and this is why the electronic yaw damper is common nowadays.'

Hi Paul,

Yep, another reason for yaw dampers, on multi engine aircraft anyway, is to allow for lower take off speeds. Many (most?) multi engine aircraft are fitted with a larger fin/rudder than 'normal' stability requirements would dictate. This allows the aircraft to remain controllable at a lower speed following an engine failure. This means that we can either safely take off from a shorter runway, or lift more weight from a given runway. The downside is that the aircraft is now snakes in the dutch roll mode, especially at high altitude.
a problem completely solved by the yaw damper.

Yaw dampers are good. Flight Attendants don't like yaw excursions while they are working. Grumpy bun runners means no coffee for me.

Dave