They have always made 2WD Jeeps, beginning with the Willys VJ Jeepster in 1948, continuing with the DJ series, and then 2WD Cherokees and Wagoneers. But the JK was the first "Jeep Universal" chassis (i.e. the 1/4-ton small truck tracing it's lineage back to 1941) to have a 2WD version.
Avoid 2WD versions of popular 4x4's. I knew somebody with a 2WD version of an International Scout that he bought new as a tow vehicle. No dealer would take it in trade and nobody would buy it. Then one day it burned and was totalled.