with all due respect I'm not sure what those pics are supposed to prove? You are not suggesting that one can hit a serve with downward angle about 45degrees as you seem to be implying here?? This pic, as well as the previous ones, are just optical illusions due to the position of the camera.
Sure, one can, and the pros do, hit the serve downward. But the angle is around 5degrees. if you are not a pro with high serve speed and high rpm topspin you just need to hit topspin serve up.
There's actually a pretty cool article by Broody (or Cross) about so-called acceptance angle of the serve. He evaluates how much up or down you can hit a serve depending on the speed and rpm. There's no much of a margin.