I think you are giving an apples to oranges comparison.
Yes, I'm perhaps being slightly provocative. It is as you rightly point out completely different in technique and outcome in terms of potential damge to the aircraft, in that we expect to pack our glider into a trailer after a field landing whereas we want to walk away from the powered aircraft in one piece. I can't remember (it may have been you) who said it but once the engine quits the aircraft belongs to the insurance company.
Edit: by the way would you still have the same opinion if the engine failure was in a Cub with tundra tyres instead of a 172? Both powered aircraft after all. Plenty of Cubs knocking around.
I understand what you are saying but I still stand by my assertion that the mental picture we give vanilla PPLs of engine failure is wrong. It's not something that may cause imminent death, it's something that unless you are completely out of luck will lead to a safe and successful outcome, for you if not for the aircraft. It's nothing to worry or loose sleep about. You could say the same for field landing a glider. Many glider pilots have come unstuck purely through bad luck putting down in a field. Again I must stress that I'm putting a UK centric view on this. Most of the UK has fields you can put a Jumbo down in. Fields we are not in short supply of.