That tiny delay in the presets

I've noticed that a big portion of the piano presets have a tiny (7-40ms, ~5% mix) delay turned on in the effects section. Does anyone know what the thinking is behind this, if there is one?

Also, in binaural mode, is the time it takes for the sound to travel from the piano to the ears included? And is the audio card buffer delay subtracted? nitpicking, I know..