Meta4's post sums things up very well. Collisions that seem very simple can be very complex things to analyze - hence the observation that a dramatic fall can cause little damage, while a minor, low speed crash can cause major damage.
I had a couple of crashes that scared me when I saw them happen, yet the only damage was a small nick in a prop in one crash (replaced), and actually no damage at all in the second crash, except for tree sap that needed some Windex on a paper towel to remove. One thing that happened in both cases was that two of the snap on landing gear extensions came off (just had to snap back on) - obviously some of the energy was dissipated that way...a good thing. Also, one of the front legs partially folded - built in energy dissipation.
Using prop guards can be a two edged sword; they can prevent a crash by allowing contact with a surface like a wall, without affecting the props, yet if you fly into bushes, the guards can become "tree hangers" keeping your drone from falling to the ground. There is, of course, a minor performance hit due to the extra weight whenever they are attached.