First, as a disclaimer, I wouldn't be caught dead in a GM. Their stupid nanny-state idea of how to build cars pisses me off. The door locks are but one symptom. The On-Star feature where they can listen into what is going on inside your cab without your knowledge is yet another symptom. And lastly, the fact that they have data in the vehicle computers that can be pulled out and used by your insurer or the courts against you, and GM doesn't tell you that the vehicle records your actions, is the last strike against GM¹.

The best reason I can give for why someone would spend that much time getting rid of the vehicle locks is that it is his vehicle. He paid for it, he owns it, it is his. As such, if the customer wants the doors to not automatically lock, and the manufacture can make that happen, it should happen. Period, end of discussion.

Now, what I would recommend is that if a feature like this pisses you off, you should not buy the piece of GM crap in the first place. 

¹  Oh, what's that? You GM and Chevy die-hards can't believe that GM would do this to you? Fah. You're just blinded by your brand loyalty. Here's info on who is keeping what data on you:

http://mfes.com/cdr.html