You'd have to be an absolute idiot to get the sedan over the wagon. Sedans are so completely and utterly useless when it comes to hauling or utility. Wagons aren't associated with being a mom car, full size SUV's are.
I honestly think the WRX wagon looks a lot better than the sedan counterpart. It looks more finished. It's the same with all the Imprezas, I think so anyway. I think the new Legacy sedan looks better than the wagon counterpart however, but I still think both look extremely nice.
I really don't care what people think of the car I drive, so long as it work for my needs, the WRX wagon does.