Good question, I'll give it a shot. I think the main reason is weight and their small size. However, some road bikes these days are using cantilever and disc brakes. You won't see v-brakes on a road bike because road levers don't pull enough cable for them.
Hey quick response! I forgot about disc brakes because my bike is a ten-year-older - 1999 Kona Caldera but still going strong!
For road bikes I know it is important to keep the weight down: well also for MTBs mine weighs in at 27lb with a steel frame (I'm sure the Al frames these days weigh a lot less but maybe a little too ridgy).
I can't really see that there be much difference in weight between the brake types but all counts on a road bike. Just curious as to why this seems to be the (until recently, as you said), the norm...
Well if you're going to thrown down the gauntlet, I suppose I HAVE to reply...
I'm sure I don't know the whole history but I'd say:
1. tradition - calipers was the first design that performed well and designers have stayed with them (there was some really goofy designs in the 1800's)
2. simplicity/interchangeability - easier to install and adjust
3. cheaper - when you include the extra frame work required for posts, they're probably a fair bit cheaper
4. more aero
5. they're strong enough - if you can skid the wheel or flip the bike, you don't need stronger brakes anyway
6. lighter - this is probably true if you include the frame posts and the extra strength the frame needs to handle the brake stress with cantis
Can't think of anything else. Some of the reasons for switching to cantis was to give clearance for bigger tires and to allow for better shedding of mud. Those are some of the reasons touring and cyclocross bike have them. Can anyone think of anything else?
Yeah, I think people got most of the arguments down. Simpler design means less trouble with them, easier to work on, and so forth. Very light as well. Very easy to find parts for, unless it's a bevel pad setup like I used to have on an old junker MTB I owned where you have to struggle for parts.
Why is it that they make adult bikes that'll generally work for 5'9" or above, yet when you pedal these same bikes they only work for someone who is 5'4" or so?
Also, the one bolt design allows for hot swapping during races. V-brakes, canti's etc., all require a post on either side. Calipers don't. One bolt off, slip off old brake, slide on new brake, re tighten. I actually saw a mechanic hanging out a support vehicle window swapping a front brake so the rider didn't have to stop.
Dedicated scholar of bicycles