"Reagan should have bombed them back into the stone ages on January 21, 1981."
Well first of all they released the hostages on that date (I believe)... secondly he didn't want a military confrontation with them because they were a useful bulwark against the Soviets.
The hostages were released just after noon on January 20th, by the 21st they were safely in Germany. By the time Reagan took office, the Soviets were totally bogged down in Afghanistan and wouldn't have done a thing about Iran.