I'm late to reply but for me it's step 3 that's the problem. If you + your hands are super cold getting your shirt and jacket oriented and on is a huge pita. The robe you just toss on and then everything slows down and you can stay warm taking your wetsuit off without stomping it into the pavement.Here's what I don't get......
If it's cold you:
1) Pull your wetsuit down to your waist
2) Wrap a towel around your waist
3) Put your jacket on
4) Proceed to take off the rest of your wetsuit and put your pants back on
How is the changing poncho helping to keep you warmer? It just seems like an extra step that's unnecessary to me.
I understand the argument that it's less likely to come undone. That's a valid point, but that doesn't happen to me often enough to justify a pancho.
Plus as others have said they can be a lot thicker than a towel. After I rinse my suit I wrap it in the poncho and it absorbs a ton of water and the suit is half dry before I even get home. I can do sunset session one day and have a dry suit for dawn patrol the next if there's still swell.