The issue is that those hotkeys are running out really fast. And there are way more useful things to do with modifier keys during node transform than wrangling the frames.
For example see the discussion in the other thread:
Alt key during node transform already toggles whether the node is connected or disconnected onto underlying node links. So you can’t have the same key also do unparenting from the frame. The shift key is free (or rather isn’t but does quite useless operation right now), but even that one could be better used for toggling auto-offset on the fly.