Why?
I'm glad there was no explanation. I'm so sick and tired of explaining everything. It is the first time that NY has been devastated in a film in ages and it was done by a monster who looked fucking cool. Space creature, ocean creature, government experiment gone wrong, white trash family. Take your pick.
The websites and viral campaing led you to believe the oil drilling was a coverup as the Japanese company was unearthing the creature from the depths of the ocean. If they go to the trouble of putting all the clues out on the internet, like the whistleblowers notes, why not include it in the movie? Especially since the movie was short enough as it was, so it wouldn't have added to much time. Hell, one of the army guys could have filled them in.