It seems that VMware didn’t just change the name of its flagship product, from ESX Server to just ESX, but also slightly changed the licensing scheme.
Note that VMware channel is still obliged to sell VI licenses with a 2-CPU increment, and this change currently affects only the way customers bind the acquired licenses to their hardware.
Why VMware is doing this? The official Q&As clarify that the 2-CPU license minimum requirement was not well accepted by some SMBs.
Unfortunately the current HCL has a very limited number of supported servers with single CPU, so VMware will have to work on this extensively to make VI3 a more appealing offering for SMBs.