In residential applications, outswinging is not the norm. The reasons are two fold. First, outswinging doors are more exposed to the damp because the weather seal is toward the inside edge of the door leaving the door edges exposed to the outside air and rain. Second, outswinging doors are more susceptible to the wind slamming them closed or tearing them from the hinges on the backswing. If your application is well sheltered from water and the doors can be latched open or are never exposed to the wind, then there is no reason you can't swing them out. Most commercial building are required to swing doors toward the outside if the door is a code required exit.