I've actually figured out a few things relating to folding in recent years. If you take a bite out of a slice with the sauce/cheese on the top, the sauce/cheese make greater contact with your taste buds, which, in turn, gives you greater sauce/cheese flavor. If, on the other hand, you fold the slice, the first flavors you get are crust, and, because the crust starts breaking down/releasing it's starch, you never really get the same taste impact from the sauce/cheese. Now, on Neapolitan, the crust/char can be the start player, so maybe someone might want to maximize crust flavor by eating the pizza folded, but, at the end of the day, I think it should really be about balance, and the most balanced tasting bite of pizza is sauce/cheese up.
Folding is a very utilitarian method for portability, but, for those that can sit and eat pizza, non folded pizza is a more flavorful experience. This is why I don't eat calzones.
And my thoughts on folding expand across all styles. The bulk of NYers fold their pizza. I grew up folding my pizza. If you really close your eyes and savor the flavors, though, you see that folding robs you of part of the experience.