You could perhaps specify the argument in the macro itself with some placeholder like "%arg", which gets replaced with whatever you follow the macro command with. So, if you wanted a macro that makes you point dramatically at someone (let's call it "~dramapoint"), you could have it as:
.strike a pose and .point dramatically at %arg
And then when you type "~dramapoint Steve", you'd get:
"You strike a pose and point dramatically at Steve."
It could also help for shortening commands: I.E., "drive katana to %arg" could be mapped to "~d", shortening the command for driving your motorcycle to "~d w w n e" to drive west, west, north, east, etc. instead of having to type the entire phrase every time.
I get that macros are supposed to be pretty bare-bones, so I understand if this is asking a bit much, but it's a little piece of functionality that I find myself wishing I had access to when thinking of what macros would make life a little easier for me.