Resulting out of conversation on patch for T145674 we've tried to pinpoint user experience usefulness on 'notice' type inline form messages.
While 'error', 'warning' and 'success' messages all have distinct use cases, there doesn't seem to be clear such use case for 'notices'
As part of current demos, v0.30.4:
The demo already shows, mostly those messages don't need to be dynamic, rather labels or inlined help texts.