However, I do think the term "cap" is misleading. There are indeed benefits after you hit it. However, we use the same terminology with expertise and no one seems really upset about it. After 26 expertise, you no longer reduce dodge chance, and we call it a soft cap. After 540 defense we no longer reduce crit chance, but even remotely referring to it as a cap seems like voodoo to some.
After lots of thought, I like referring to it as a minimum...however, seeing someone calling it a cap doesn't cause my blood to boil or anything. I just make sure to toss out the caviat to them that defense has benefits after it stops reducing crit chance.