> just trying to think of a real use case.

Macros help lisp to adapt to about every new idea/trend without making
changes to the language as such.

One simple use case that comes to mind is conditional compilation, eg
inserting some code only if a certain flag is set.

> i'm hoping macros can be scoped to an object like instance methods....

I personally think it would be a good idea to somehow restrict macro
expansion to specified classes/namespaces. Otherwise, just of what
would happen if you define a macro foo and use some library that
defines a method of the same name.