To me, strategically, taking Okinawa does not give the U.S. much. The firebombing raids and eventually, the nuclear strikes were staged from Saipan and Tinian. The explanations I can find say that Okinawa was going to be used as a staging base for the eventual invasion of Japan, but the original War Plan Orange did not call for such an invasion.
Okinawa offered several things to the US.
It also allowed smaller bombers like the B-26 to operate against Japanese targets, and additional fighters to operate as well.