A time delayed message in my opinion would be an useful edition to DQMH.
I understand that helper loops can be used to do timing with event structure timeouts. This becomes problematic when you need arbitrary number of timing instances at runtime. I agree resource intensive timing should be in helper loops but you may want to set up a heartbeat or check a certain signal periodically.
I did this in my application by creating a child of the messaging class and extending the class with AF style timing. But it would be nice to have this naively in the messaging library.
AF Time-Delayed Send Message VI: https://zone.ni.com/reference/en-XX/help/371361R-01/lvcomm/af_td_send/
We encourage and enforce the use of helper loops.
As you mention, it's possible to implement it if you need it.