We're considering these implications right now, so yeah it's preposterous, but you'd be surprised (or maybe not) with the number of people that would dismiss these considerations as pointlessly delaying progress.
These planets are also so damn far away that we’d never hear from any ship we could possibly send out there again. Even if we could send information at the speed of light. It would be pointless.
Given that after arriving everyone could just die from some weird protein floating around in the air and you might want to look before you spend the entirety of our economic efforts reaching it… erm, look before you leap.
