If you resist arrest, then cops WILL use whatever level of force necessary to subdue you. To do otherwise would mean that anyone willing to resist would be immune from arrest.
If you make the cops have to use force, then bad things can happen. In this case, the guy got a heart attack from the exertion.
Use some common sense. If someone says they cant breathe when they are in a choke hold and others are holding his face to the ground, do you think maybe a bit less pressure would be in order? How about when he is clearly in distress after they get off him and no one renders any type of aid? Does that mean anything?