"Rain" is meant to be a snapshot into a particular mood. The simplistic text hides inside the shadow of dense minor harmonies to evoke the feeling of being surrounded by rain clouds, and the uneven meter serves to unsettle the listener, particularly through the use of "the" on downbeats rather than pickups.  The overall gloomy feel of the piece allows the performers and the audience to wallow in a collective misery for a while, because sometimes the only way to cope with difficult feelings is to sit with them and share them with others.