Mazda has been aware of and working on this issue since October of 2006, and this month it began installing a "countermeasure" in all Mazda3s being built in Japan. For those who have already had their cars broken into, in some cases Mazda has agreed to install a reinforced door lock assembly and a protective plate to prevent the same break-in from happening again, though it has not offered to repair the dents. At this point, Mazda does not consider this "trick" a defect in the product and it hasn't decided whether or not all Mazda3s will be called back to have the countermeasure installed.
We think they should be voluntary called back and have the countermeasures installed. While a thief will get into your vehicle one way or another if he wants to, being able to do it without smashing glass or looking terribly suspicious makes the Mazda3 a much more tempting target. Still, no one should leave valuables out in the open and give criminals a reason to target your vehicle.
Thanks for the tip, Rich!