You know, I actually wrote about it some days ago. That when a civilisation becomes technologically advanced enough, it would not need to do the exploring itself but have robots do it for them. I agree with this point.
But I also think that we should have some amount of human presence in other planets too. There are many things we do not have control of and if they destroy the entire Earth (despite our best efforts), there should be self sustaining colonies in other planets to keep our species going. That's what I feel anyways :)
RE: How Long Do We Have Before A Doomsday Event?