What's with Mars?

Growing up I wanted to be an astronaut. The thought of going into space was a very cool idea. Zero gravity and walking on the moon are still fun to think about. However, I honestly don't understand the fascination with Mars.

NASA spent over $500 million on the latest Phoenix Lander to find ice within 20 inches of the surface. That's half a BILLION dollars just to find ice! That's not ALL this lander will do of course. It will also take some 3D pictures and test for gases in the atmosphere. It will also test the soil to see if life COULD live there. I'm guessing this means crops.

This is all so we can send people there to live and work for lengthy periods of time. Perhaps for the remainder of their years since NASA doesn't have a "round trip" plan yet.