When God gives a people up, or gives a people over to themselves, He does this for redemptive purposes.  God allows the sinners that suppress the truth in unrighteousness to go further into their own sin.  He allows them to feel the consequences by giving them over to themselves, releasing them from His divine restraints.  
Paul lists many sins that are representative of all sins as the people, the culture, spiral downward into debauchery.  But all of this has redemptive purposes.