Interesting to read about these 'rust issues'.
I had a 2004, 250k on it over 14 years, very minimal rust. It is not a Mazda issue, but a salt/care issue. I would definitely hate to deal with that on a regular basis, but it seems you got the max life out of it!
Sorry to disagree, but it IS a Mazda issue. There are many other makes and models that are exposed to the same environmental conditions, that do not deteriorate like Mazda's do.
As for care. Well if you've never lived in a snow belt like I do, where road salt is used from November to March, then you have no idea what it's like to deal with. There may not be a dry day for weeks at a time. You could wash your car everyday, and once you drive a few hundred feet, it gets soaked in salty slush again.
The problem is also not the exterior of the car. Going through a car wash might make it look clean on the outside, but underneath the car, as well as inside the fender wells and all the other nook and crannies, it is still soaked in salt water. They rust from the inside out, not from the outside in. Trust me, no amount of cleaning will get it all out.
The sheet metal on these earlier Mazda's is of poor quality, and Mazda did not make any effort to provide protection. No undercoating etc.
Mazda also has a reputation for poor, thin paint. I can personally verify that, as my roof had to be repainted due to small rust bubbles....after only three years and less than 20K miles of ownership.
I've read that Mazda's supposedly improved after 2010, but I'm not convinced.
