Neither of macros expands in trigger comment (it's called trigger description since 2.0.4).
I would like to use

{MACRO}

and {$USER_MACRO} in trigger comment to include

{TRIGGER.COMMENT} in notification's body in actions.
This is example from real life:

I have macro {$UNIX_ADMINS}=>"John Doe, Jane Roe and Pavel Timofeev" or there is same people in host profile contacs.
I added new trigger (for ex., "Free memory on {HOST.NAME}") and wrote in its comment/description following phrase:

"If you've received this message please call {$UNIX_ADMINS}!"
or
"If you've received this message please call {INVENTORY.CONTACT!"

Then I created action where I defined conditions and wrote in body: {TRIGGER.NAME}: {TRIGGER.STATUS}
Last value: {ITEM.LASTVALUE}{TRIGGER.COMMENT}

(or

{TRIGGER.DESCRIPTION}

)

as result we would get message with following words in body:

Free memory on server1: PROBLEM
Last value: 5%
If you've received this message please call John Doe, Jane Roe and Pavel Timofeev!

If macro worked in this case it would be very useful.
We have day and night duty officers that have to respond on any messages from our monitoring system.