Sometimes hosts could use the same template because they only differ in some little details (for example service names "ntp" vs. "ntpd"). So in this case one could use a macro within the template to use the appropriate value. But setting the macro value manually or by an additional mechanism isn't a good option.
Therefor it would be much better if setting a host macro's value is done with auto registration respectively network discovery. But unfortunately there is no corresponding operation type in the action configuration.
The only alternative is to create additional templates which are linked to the original one and just override the original's macro value.

So it would be nice if the action configuration gets extended by an additional operation type like "Set host macro".