Usually, for PvPers at least, macros are a string of maybe one or two abilities that won't cause a GCD conflict, or just used to take less space on your bars.
For example, having a macro that would stun the person you have targeted when you hit the "E" button, while at the same time, if you press "shift + E" it will stun your focus target.
You have a variety of other useful macros, but it's rarely what people actually believe them to be. Having 10 abilities stringed together to do all the work for you, ect...