[Zooks527]

Originally Posted by scrape1

It's most likely programmed that way to keep BMW from being sued if someone accidentally bumps the gearshift while in neutral, setting the car in motion unexpectedly.

^This.

Originally Posted by akuan99

I believe it was designed for safety issue.
It was prompted by the infamous Audi 5000 car unintended acceleration.
You can read about this here http://www.autosafety.org/audi-sudden-acceleration

Exactly. After a number of incidents of people nailing someone to a wall by flooring the gas coming out of park or neutral instead of pressing on the brake, the shift lock function was implemented.