Idea: (edited using input from @jcarlson)
The diagnostic logs in ArcMon are great, but it seems like an unnecessarily complicated way to view something that, in other contexts, is simply another window or tab in the expression builder.
A simple window would be awesome. And maybe not just an "Arcade Console" window, but a tabbed "Logs" window.

The different categories of logs appear as tabs as needed. Maybe we could get a logs tab that captures Arcade Console() messages as well as messages from Python and GeoProcessing. As it stands, if I'm looking for feedback on the things I'm doing in Pro, there are a number of disparate tabs / panels / popup windows to look for to see these.
Old idea:
When developing and testing attribute rules:
Would it be possible to view log info when the rule gets executed?
https://i.stack.imgur.com/KmGZP.png