The problem is that commercially, a splash down and recovery may not be viable - remember, NASA used military vessels for recovery. The cost of recovering the stages could be justified in the budget as training exercises for the Navy. It may be that the cost of extra takeoff weight in fuel is not more expensive than the man hours needed for splashdown recovery. I don't know for sure, and have no figures to pull out of my rear on that, but it's the best reasoning I can come up with for why a space program might choose to land and reuse, rather than splash and reuse.