I am really surprised this didn't kick up

Just going to toss this into the discussion... my MP Chassis Manual has a section on structural chassis mods and covers subframe connectors. It's mentioned as something you should do to any Mopar you intend to modify for performance. If the factory engineers didn't think it was necessary or beneficial (or would potentially compromise other parts of the unibody structure) I don't think it would have been published in those books (written by Chrysler engineers) for the past 40-some years.