Personally, while I would rather not have a front one, and have gotten a ticket when I didn't realize my front one was missing (along with the mounting brackets) I can see why the government would still want us to have them if for no other reason but to aid law enforecement who might only be able to get a glimpse of the front of a car.
The "aerodynamics" argument is a pretty weak argument, since all of the new pedestrian safety laws are changing cars to make them less aerodynamic by requiring more flat, and taller front ends on cars. The new mini is a good example, because they are easy to compare side by side. The front has become much more blunt, and also taller. Both of which would make a vehicle less aerodynamic. The government isn't above putting safety over athetics.
As far as the air blockage thing, this is more of a problem with North American cars, as our plates are much taller than in other countries, where they can hide their places in much narrower horizontal stripe. However, when I re-installed front plates in my last car, after running it without it for, apparently, over 3 months, I noticed no difference whatsoever in power, or fuel consuption.
As far as "excess damage" caused by the brackets or bolts...they would just require, by law, that the brackets would need to be redesigned. Wouldn't that be just as viable a solution? Or even, why not eliminate the back plates, too, for this reason?
As far as the storage of the plates, there are many people here that I know (granted...not the smartest pickles in the jar) that thought they didn't get two plates in the mail, when they actually did, but they nested so closely together, and so tightly and stuck-together, that they thought it was 1 plate, and had installed both plates on the back. I couldn't imagine that storage costs would drop so significantly by only storing 1 plate, since the two identical plates that, because then nest, take up such a small amount of room. Much less that two different plates would.
Again, I would love to not need one...however, I can see why they are there.