> So things generally funnel very well through the forum/mailing list and you know that a post in the Feature Request forum will request a feature, so you can mentally prepare for it.

That helps address the under appreciated mental cost for dealing with an open ended inbox.

If you don't know whether the new message is related to 1.) expression of gratitude, 2.) complaining, 3.) feature request, etc., you have an added amount of anxiety when opening the message to figure out which kind it is.