Well, not sure if I would make it a feature for Trinity, but if you create a macro with the following, you can toggle the hotkey text to hide/show:
Code:
/script for i=1,120 do if getglobal("TrinityActionButton"..i.."HotKey"):IsVisible() then getglobal("TrinityActionButton"..i.."HotKey"):Hide() else getglobal("TrinityActionButton"..i.."HotKey"):Show() end end