I'm A Banana
Potassium-Rich
Hussar nailed it, I think. Armor is passive, weapons are active, and in a game focusing on the heroic, they're going to focus on action.
But it's not exclusive. Races of Stone is a good resource, and Hammer & Helm is even better. If you get something like Death Striders, you can see armor that mutates into siege engines, making them VERY active, indeed.
In fact, now that I think about it, adding the Death Striders to my campaign is what caused people to sit up and take notice of armor, again. A sheet of metal is one thing, but a sheet of metal powered by necromantic energy that shoots lasers and powers jumps and can fly around and that you can't really penetrate without destroying....that made the party go "Woah."
But it's not exclusive. Races of Stone is a good resource, and Hammer & Helm is even better. If you get something like Death Striders, you can see armor that mutates into siege engines, making them VERY active, indeed.
In fact, now that I think about it, adding the Death Striders to my campaign is what caused people to sit up and take notice of armor, again. A sheet of metal is one thing, but a sheet of metal powered by necromantic energy that shoots lasers and powers jumps and can fly around and that you can't really penetrate without destroying....that made the party go "Woah."