Multiple Security Strategies for Van Security? Why would I get more than one type of security device?

This video shows an installation to a Ford Transit Custom Van where we implemented Multiple security strategies on a realistic budget, we did the following;

*Beefed up factory locking system? - To help prevent the original Ford Locking being circumvented and to help prevent the factory alarm being switched off by a lock picking key.

*Fit extra security locks - so that the van doors still will not open even if they get around the manufacturers security.

*Beefed up factory alarm system - So that the alarm will go off if someone gets into the load area by using excessive force; such as cutting a hole in the side / roof, or crowbarring the door off the hinges. ???? 
*Protection against side door folding - by adding a switch to the top of the side load door we are reducing the risk of someone folding the side door down on this vehicle as the alarm will go off as soon as they pull the top of the door out.