DJ,
From the above, I assume you got a "D" in A Level physics
You are 100%......wrong!
Pressure (stress) = force/area
Do not get confused with the pressure on the brake pad backing plate and the area of the friction material.
Take the following:
1. Brake Pad "A": Backing plate area = "1", friction material area = "1"
2. Brake Pad "A": Backing plate area = "1", friction material area = "0.5"
Force applied due to hydraulic pressure will be the same for "1" and "2".
Friction force generated between 1 and 2 will therefore be the same.
However, STRESS on friction material "2" will be 2 x stress on friction material "1"...therefore the heat generated wqill be more and the wear rate will be worse.........
Enough.