I think it's pretty clear what's going on:

1.  The new "management" at DAZ used to use this store software (Magneto) and insisted they change over to it since the existing store software is such a jumble of code and errors; and

2.  Magento is a physical product software package, i.e., you're shipping physical (crafts?) products to a person.  Since DAZ is a digital store, they are trying to shoehorn a product into a shopping cart not designed to handle the product.

So, I conclude, the software can't deliver EXE files, so ZIP files it is.  Unless DAZ is willing to do a complete system re-write to deliver their beloved installer files, ZIPs it is.  Because........DAZ bought a LICENSE to use the shopping cart.  They have no authority to modify it, since they don't OWN the source code outright.  Despite Randall coming in here just a few months ago, saying unequivocably that ZIPs would NEVER be the delivery method, here they are.  Lots of other things will be impossible to do as well - think about what you can and can't do when you check out at a Michael's Craft Store.

on edit:

Magento may be open source, so the lack of customization is even more puzzling.