war of the worlds

I wanted to watch Spielberg's War of the worlds. I did yesterday but was quite disappointed. The movie has all these aliens who land on earth for no apparent reason other than drinking blood. The main characters contain 3 psychos, Tom, who is a bad father, the son, who is just trying to run away. The daughter who keeps screaming in high frequency to break a mirror at the slightest hint of danger. All three keep running around escaping a 30ft alien tripod, in which they are pretty successful at (because they get to live). And in middle of all this there is tim robbins who is another psycho. In the end, its all over because the aliens die by themselves because earth's air and water arent suitable for the aleins (like it is for humans). With technology years ahead of humans, they would not infer that but just go on to kill as many humans as possible.
They should've asked the humans if the air and water are good for the humans.