I think, one of the problem here, is the universality aspect of USB. When we had different plugs for different things, no keyboard could pretend to be a mass st

I think, one of the problem here, is the universality aspect of USB. When we had different plugs for different things, no keyboard could pretend to be a mass storage device and vice versa. Now, when you plug something into your USB port, it could be anything. It is similar to the scripting languages, Microsoft included into their office products. Before their where also some scripting possibilities in office products, but most of the time not that powerful. When they did it into the most popular office suite existing, the way for a new kind of virus was paved. The universality of office scripting also made the products more vulnerable to attacks.