What I really want to know is why doesn't the GPU industry switch video cards in this price range to a PCIe x4 interface (and the lowest performing cards to PCIe x1). It has no effect on the performance of those cards, the PCBs will be cheaper (less copper), and every OTHER expansion slot industry is doing it constantly to put devices into smaller slots (especially things like NICs and RAID controllers). They will still work in all longer slots, and also fit into smaller secondary and tertiary slots.
I could imagine this being any of four reasons:
1.) There may be a performance improvement in 1 obscure game at an insanely high resolution, which may rationalize the manufactures in making these for PCIe x16.
2.) The PCIe x16 slot provides much more mechanical strength to the card than a PCIe x1 slot, reducing breakage in systems that come pre-assembled and shipped with the card installed.
3.) Using a smaller slot will result in the uneducated putting the graphics card in the southbridge slots in motherboards, which will result in incompatibilities, possibly less performace, and definitely lots of tech support calls when systems do not boot/do not detect cards.
4.) Specialty PCIe x1 models can be produced and sold at an extraordinary price compared to standard models.