Physics 101.
Fork dive on rear brakes too. The fork dive is caused by a weight shift when either brake is applied. The shift puts more weight forward due to change in momentum. Try hitting just the rear and see if the front doesn't drop and steering get heavy. The real problem occurs as weight is removed from the rear tire, reducing friction coefficients of the tire to pavement. When the rear locks up that magical moment is the point where friction cannot overcome momentum. Using the front brake alone shifts the weight too, but because the weight is driving forward the friction coefficient increases with the braking force applied. Don't believe that? Watch the bozo's doing stoppies and ask yourself how much traction the rear tire has 3 feet in the sky.
Rear pad wear is proportional to usage. Use it alot, wear it out fast. Use it never and it stays like new.
End of lesson.