When grouping many nodes on a flow, ist is risky to delete all these nodes with one key.
I think it is a good idea, to delete the complete group only after confirmation dialog. An another reason to use groups, because it is more secure for the nodes that they can be securely "stored / contained" in the group
I think it happens to all of us from time to time, that we erroneously delete nodes or even whole groups. Thankfully, there's a brilliant undo feature that brings those back again with two clicks or one key-combo (in my case: crtl-Z).
I'd thus vote for keeping it as it is...