That's not really the reason why
I don't have the benefit of years of engineering schooling, as some of you guys do, but I believe the reason is so that the vehicle does not nose-dive when applying the brakes. I believe when the brake force is more evenly distributed, the vehicle weight is distributed more equally on all 4 tires, braking efficiency is greater, the vehicle is more stable, and perhaps the overall braking distance can be decreased. Naturally, electronic stability control also plays a role in this, in the typical newer vehicle
I believe it's all about safety, not about having the front brake pads last longer
Which scenario is more desirable?
And which scenario would likely produce shorter braking distances?
You apply the brakes, the vehicle nosedives, the rear tires have poor traction, and you just about hit your head on the steering wheel
You apply the brakes, the vehicle remains level, all tires have good traction, and you don't hit your head on the steering wheel