After playing around tonight I find in the heavier pots and pans that the upward pointing handles definitely aid the rotation to pour stuff out. When the pot is heavy, using the wrist and forearms alone is insufficient. The vertical angle recruits the biceps and shoulder muscles, both spreading the work load and recruiting larger muscles for the task.
Think of a ladle. When you pour out of the side of a ladle you lever the top of the handle downward. Similar effect when the saucepan handle angles upward. You don’t just rotate the wrist to pour, particularly if you need both hands on the handle. The handle becomes a bit of a lever, the forward hand operating like a fulcrum.
