well, look at the stock front brakes.  they are held on by a 14mm bolt(17mm head) into a caliper mount almost 3/4 inch thick.  Toyota did it that way because under high traction, with big tires, a loaded rig, and panic stomping of the brake pedal that little 10mm bolt with the nut spacing it out away from the mount will shear off like a donut at a cop convention.

I agree, no matter how the caliper is clamped down, the bolt is still being used in shear.  You could tighten it down against anything, when you hit the brakes, the bolts gets a shear load.  The only way to get more out of the bolt, is if the shear load was entirely on the shoulder instead of the threads.   

I like the caliper mounts.