Keeping (or getting) the wings level is absolutely key when things start going south, no question about it.

The blanket advice to not epoxy the wing centers isn't a good idea. Some trainers, such as some variants of the Avistar, don't have the metal bar in the wing center, and rely on the epoxy joint between the center ribs for a lot of the strength.

It's not possible to say for sure, but if you had epoxied the wing togeter, you might not have even bent the metal bar or damaged anything in your case. Personally, the movement of the wings I've seen from the "no glue needed" wings worried me a lot more than any possible reduction in damage from the wings moveing seperately. I've seen wings that had a bit of movement from the metal bar, and I suspect the wing would have eventually worn out from this. No way to know, however.

Another problem with some of the no-glue wings is that not all of them have tape or something to hold them together and seal out fuel and oil. If fuel can get in to the wing center section, it will weaken it badly. A good epoxy job will prevent that as well.