Thornmail changes

The idea of thornmail slowing attack speed seems really silly. So I was wondering if we could instead have something else? If I really wanted to defend from aa heavy champions I think Randuin's Omen or frozen heart is a better choice. I feel like these are better for defensive and initiating purposes. Frozen heart you initiate with an ability and cause havoc trying to be near as many people. Randuin you charge in and use the active and try to become a pin cushion so your team can kill people. Thornmail I feel needs to either lose the aa attack speed or maybe even get something like an AoE movement speed debuff.