Two things...well three really.
First, be sure of your information before you spout off.
Second, the reason the Iranian Airbus was shot down had nothing to do with being able to actually see the target visually. That aircraft's transponder was deliberately programmed to register as an Iranian fighter jet. From one who is in the business of these type of things, I know. Each aircraft is distinctly and individually programmed so that ATC can acurately assess and control air traffic. So I ask you, who is really at fault in that situation?
Thirdly, the incident was amidst the Iran-Iraq war in a very tense Persian Gulf. US Naval assets were there to protect American shipping, and having already suffered attacks and aggression from both sides, I believe the crew exercised their best judgment in defense of their ship given the information they had from their "primitive" equipment. What decision would you have made were you there in that situation? 90% of people would probably have pulled the trigger too, and the other 10% would have placidly allowed themselves to be fired upon like the sheep they are. Yet you might argue, "But they wouldn't have been, because it was an airliner!" and again I ask, How in the heck would you be able to tell without a visual confirmation?