Because the people don't need to know everything. Area 51 was, in my opinion, first used as a base to set up nuclear test sites in the surrounding areas. This is probably what the Roswell Incident really was. Yes, it's true, governments try to cover up for their past mistakes, but the notion you're proposing is ridiculous. If this were true, wars could be won much faster if we just unleashed some of our "insane centuries ahead technology" and let out a can of woop-ass on our enemies. If you're going to claim conspiracy, have some evidence to back it up other than, "well that evidence proves us wrong, so we're going to come up with this elaborate conspiracy theory along with a whole slew of easily refutable weak points to make our case." I'm tired of that. If something doesn't fit with you people, you find some ridiculous excuse to throw it out. You're not a scientific school of thought, you're a religion. Science accepts new facts and admits that it was wrong in the past, so that it can get it right in the future. Science searches for truth, it does not search for facts to prove a truth it already believes in. You people excpet no other evidence, and are working towards a final goal with your "evidence". That's just plain dangerous.