These little things are better than nothing, but honestly, you're mostly talking about the least problematic things in Madden. Tattoos, field, uniforms are secondary to the things that actually need to be fixed.
I think when people think of modding, they think there will be animation/physic changes, probably due to how open something like Skyrim/Fallout is, but I don't think that will be possible with the Frostbite engine.
As I said, this is obviously better than nothing and EA should have provided PC support since 08, but I don't think the modding scene will explode until EA allows more mod support for the engine.