Like Dave says, the lock is of questionable value. It may cause a malfunction of the gun. Not a "feature" I am willing to pay for, or put up with.
I am not advocating a boycott of Remington. I'm just saying that if I was going to buy an 870, I would buy a used one that is less technologically advanced. And I would let Remington know that they lost a sale.
My pre-lock 870 seems safe enough. I can't really see the need for a lock. To me it looks like a CYA answer to a problem that only exists in the minds of people who don't own guns. It wouldn't bother me if Remington had spent the time to design one that functions properly, like Taurus did. At least with a Taurus handgun I can ignore the lock without worrying about it turning itself on.
I think 870's are a great design, but the lock feature is not a plus.