I used to toe in caliper brake pads when the ones I had were fairly cheap and flexy. My current brakes (Dura Ace and Ultegra dp's) and pads (Kool Stop Salmons) are both strong and quiet with the pads aligned parallel to the rims. Current Kool Stop inserts no longer have the ridge on the trailing edge that set the toe angle and they don't need it.

I have had both canti and V-brakes where a fairly severe toe-in was essential to quiet them down.