Only positive I can see about this is avoiding the need to purchase RT tickets.
Years ago domestic US flights would also be considerably cheaper when booked as a RT, especially with a Saturday night stay. As far as I can tell, that doesn't exist anymore in domestic US air travel. A RT is the sum of the two OWs.
If WOW air entry into this market will result in the elimination of the RT with Saturday night stay requirement for low fares, it will be a boon to all travelers.