It's for putting children in the front seat, especially in rear-facing baby capsules which sometimes don't fit in the back seat etc. That's the primary reason.
The other reason is so that Jack Bauer can escape being held at gunpoint by driving straight into another car or wall, killing the terrorist holding the gun in the passenger seat, but being unharmed himself due to the driver's airbag!
Edit: Whilst I was typing this hentaiboy posted a link to a real-world example. But in all seriousness, why would you have your children in the front seat anyway. Even my parent's generation knew that the front seat is dangerous for children, why do it now 30 years later?