The mag safety was necessary because the French wanted it, what became the P35 BHP was in response to a French military request for a new handgun.
Now, when the French passed on it and FN retained the mag safety when they sold it elsewhere, Browning was no longer in the picture. No idea why FN kept it as it added cost to making the gun and likely would have sold well without it. Certainly later in it's 83 year production run when the number one mod to the guns was it's removal, you would think FN would make a version without the safety. Costs less to make and they could charge $20 more for the "unsafe" model! Hey, it works for S&W...
Always wanted a BHP, but kept putting it off due to the cost for a decent specimen. Brownells has these advertised for $680, so once the initial demand tapers off (and any problems are discovered by the "beta tester" first purchasers) I can see these for around $650 or even less on a Black Friday sale somewhere. Might as well spend them greenbacks, they are losing value parked in my savings account...