> I will let @oconnor663 speak on why they dropped the 64-bit version.
The most important thing to us was that there should be just one version. It's simpler for everyone. But we actually did go back and forth about which version it would be, 64-bit or 32-bit. "PCs and servers will all be 64-bit for the foreseeable future" was definitely a big point in favor of choosing 64-bit words. Section 7.2 of our paper goes into detail about why we went with 32-bit anyway.
The most important thing to us was that there should be just one version. It's simpler for everyone. But we actually did go back and forth about which version it would be, 64-bit or 32-bit. "PCs and servers will all be 64-bit for the foreseeable future" was definitely a big point in favor of choosing 64-bit words. Section 7.2 of our paper goes into detail about why we went with 32-bit anyway.