This is a good idea. More generally, I would like to allow:
A "delegation" macro control type, that when clicking it it simply opens the control for the connected inner device (or inner macro). This lets you pass through very important but otherwise hard to specify things, whether they be file outputs or color gradient devices. Macro controls are intended to capture the "system" behavior, but sometimes you really do want to expose the full behavior of some of the interior parts.
Would be nice to have a file save dialog in the macro properties options. This would allow us to build macros that users A) tweak settings with and B) designate where it should export a map on their local HD.
I know we can make output options that allow users to connect bitmap outputs too, but the work flow of our macros we build would be so much nicer if the file save dialog for X Y or Z was rolled up in our marco properties window.