Nice using logic to solve the issue however it is wrong. Not trying to insult you or anything just that it isn't correct.
Even on the track tires are worn at nearly a 2-1 rate and the only time the rear is used is to adjust lines during trail braking( "backing it in" is the extreme example of it)
the forces are necessary accounted for in the tire size but not in the way you are stating. The tire size deals with what each tire needs to do. The rear tire needs to be wide in order to provide enough traction to get the power to the ground. The front tire turns the bike via countersteer. a large front tire does not turn as well as a smaller tire. The braking forces on a front tire are not as severe as the acceleration forces on a rear.
Also braking no matter which one will put pressure on the front tire. Braking causes a negative acceleration, putting weight on the front of the bike and taking it off of the rear. Once "X" amount of weight has moved off the rear then the rear brakes can no longer provide braking force and causes the rear wheel to lock up.
Sportbike geometry allows 100% of braking force to be applied to the front wheel and therefore allows 100% of the weight to be supported on the front wheel(endo/stoppie) On a cruiser type bike the geometry does not allow more than 60%-80% of the weight to be transferred to the front and therefore the front simply locks up, just like the rear locks up under hard rear braking on any bike