i think the fact that it was likely the only of its kind in the universe. and from what i could tell earths first real sure fire proof of aliens that cant be covered up and suppressed by the government played a big role.
"oh we just found an alien! LETS KILL IT"
probably isnt the first thing alot of people think.
although i think it was pretty silly pretty much ALL the lights went out. wouldve been a little realistic if atleast like 20 - 30% of lights were still on