There is a technical reason.
Single pivot brakes had a faulty centering spring. The springs cannot be made from a single unbent piece of wire because it would bend too much. Instead, the springs are made from a wire that has a loop in mid-air. As this loop is not in the pivot point but rather in mid-air, in the location where the centering spring touches the brake arms, as the caliper arms move the spring slides on the point where it touches the caliper arm.
A good spring would have its loop in the pivot point, so there would be no sliding motion in the location where the spring touches the caliper arm.
Why is this a problem?
Because this is an area that is prone to becoming dirty. The dirt means the coefficient of friction in the sliding motion is unpredictable. A bit of dirt on the left brake arm and a bit (but different amount) of dirt on the right brake arm means the coefficients of friction on both arms become different. Thus, the brake does not return to the perfectly centered position.
For example V brakes and caliper brakes have the spring loop around the pivot point so this uneven centering problem is not a problem for them even though they have no forced centering mechanism.
To combat this centering problem, the single pivot calipers are made with low mechanical advantage which means the brakes operate with a very liberal pad gap. However, low mechanical advantage means excessive lever force is needed to operate the brakes. For a heavyweight rider with not so strong fingers, braking becomes a major chore.
However, even despite the low mechanical advantage, the single pivot calipers are still prone to develop a condition where one pad touches the rim continuously and all the gap is on the other side. Thus, the owner of a bicycle with single pivot brakes must be aware of the details of the problem. The fix to the problem is to often clean the points where the spring slides on the caliper arm, and always add a bit of oil there after cleaning.
Dual pivot brakes are a poor solution to the problem. The manufacturers of bicycling equipment did not realize in what manner the centering spring is flawed. Thus, they did not develop a better centering spring but rather they developed a forced centering mechanism. The forced centering mechanism is possible only if there are two pivots, hence dual pivot. If both brake arms pivot around the same point, you cannot have a forced centering mechanism that is simple, elegant and lightweight.
With the forced centering of dual pivot brakes, it has become impossible to ride on a wobbly wheel. This, combined with the fact that wheels having less than 36 spokes are unfortunately very common today, mean that a broken spoke is the end of the ride unless you release the tension on the quick release of the brake (or loosen the cable anchor bolt), leaving you with only one functional brake. A 36-spoke wheel could perhaps barely work with even the forced centering of a dual pivot brake.
Also, one dual pivot arm pivots around a point which causes the pad to move upwards towards the tire, damaging the tire as the pad wears unless you notice the pad position needs adjustment as it wears.
Everyone is buying the dual pivot brakes, liking their high mechanical advantage and no centering problems so much that single pivot brakes have become extinct.
My opinion is that today the best rim brakes are linear pull brakes (V brakes). They center well, have as high mechanical advantage as dual pivot brakes (except the mechanical advantage is more in the brake arms and less in the lever so they require different kinds of levers), do not require the cumbersome cable stop that cantilevers require, and have no forced centering so they can track a wobbly wheel. Linear pull levers are available for drop bar bicycles too, although not with integrated shifters but integrating a shifter into a brake lever is a poor idea anyway. About the only problems with linear pull brakes are that in-line and in-noodle barrel adjusters needed with drop bar levers typically do not have enough adjustment range so you may need several in-line cable adjusters per brake, and that the pads move downwards as they wear so it's good idea to use thin and long pads as opposed to thick and short pads so you don't need to adjust pad position as it wears. Of course you can't install linear pull brakes on frames and forks that lack cantilever brake posts, so that's why it's important to choose a suitable frame and fork if using rim brakes. Disc brakes of course offer a compelling alternative these days.
If the bicycle has support for only caliper brakes, dual pivot calipers are the least bad choice today, although the design is a poor idea.
