Earlier Mexicos came with a very trick parts group, so that's one feature Supers didn't necessarily have.
The other reason has to do with the tubing, which was apparently some super-light stuff from Columbus. I've always been a bit fuzzy about this part of it, but I do know the tubing was different from that used in a Super, and this difference persisted until the Mexico was discontinued.
It's not clear to me if the geometry of the Mexico was different from the super...if it was, it wasn't much different.
Charles "wouldn't mind having a first-generation Mexico"
Andrews
Los Angeles