What is there not to understand WHY wouldnt they make an AGP version?
AGP boards are still more popular then PCIe boards - so that = more money for NVIDIA - also i doubt a 7800GTX would even fill the bandwidth of an 8x AGP slot.
it makes COMPLETE sense to make these cards AGP - especially since ATi isnt'n coming out with anything new why not rule the AGP and PCIe market.