My Chrysler had it too - I actually miss that feature.
To the best of my knowledge... it's not something that is already programmed yet disabled... but I have no proof of that.
I suppose it might be possible to rewire to lock the doors when you switch into drive for example. I don't think I'd be able to make it only lock at a certain speed.
My biggest peeve about the locking doors is when you press all-lock while sitting in the car - say you leave a friend in the passenger seat for a few minutes and they lock the car for safety. If they then unlock the door with the manual unlock latch - the alarm goes off, and since you're not around with the key it just keeps going.