I think you pretty much covered the how in your question. Bashing the heck out of the T-Maxx. Landing poorly, hitting rough terrain full force, head ons, rolling the truck cartwheel style, and the list goes on.
The bottom line is the front and rear skid plates serve a purpose. That purpose is to direct stuff under the truck. If the "stuff" being directed under the truck happens to be tougher than the plate, it will bend.
Aluminum is pretty soft and tends to bend easily. After multiple bends and rebends to reshape the plate, it tends to weaken. Not to mention the multiple times you have to remove the skid to do the rebending, does wonders for the plastic parts that the screws for the skid plate go into.
After a while, the aluminum front and rear skid become worthless and a pain. The stock plastic or RPM skid plates are more resiliant, flexible and inexpensive to replace if need be.