You might get more river tiles in your initial influence area. This might be a reason, but imo its a waste of a water tile, if you can use a hill just besides the rivertiles.
I also favoured river tiles in my first games, but the more you think about it, the more its a waste of an early high food yielding tile. This habit is from civ4, but since rivers won't establish trade routes any more, there is no need to build cities there.