Well, Del Potro is a giant so it's no wonder he hits the ball harder. If you don't allow him that, what is he left with? Does he have a plan B or C? Just fine tuning your game won't cut it because it's not going to work all the time or the majority of the time. But it all depends on what you expect from him I suppose. If you take away that Slam of his, he's not left with much. He's overall career so far is not as shining.
Del Potro is like your action movie where you get instant results, instant satisfaction. Your money, you think, is well spent. I can see why a lot of the guys dig him. If you give them a classic like Memento, I guess half of the same audience would fall asleep.