I think it is the human race's responsibility to explore and expand. We have already explored the earth and now it is time to explore the universe. The sheer enormity of the universe makes it inconceivable that there couldn't be life anywhere else, there must be. If we make contact with other races we help to cement our position in the universe as well as make allies.
:D i shouldn't have to explain anything, it's simple, we go extract lifeforms and study them and if they are dangerous in anyway we KILL THEM ALL HAHAHHAHAHAH :D then we eat them and see if they taste good, and if they do we make a farm and put them in restraunts
There may or may not be life on other planets. We don't know all there is to know about other planets and we may never know. Even if there is life on other planets, there is no need to male contact. Our planet and humans have survived fine without knowing or contact.