There are certain types of guns that civilains have no practical uses for; assault rifles or any gun that has a rate of fire of hundreds of rounds per minute. Those types of weapons should be reserved only for military and law enforcement use, and are too dangerous for the average civilain.
Think about countries with almost no guns. Britain is the first one that comes to mind. Now what if I told you that the crime rate in those countries are two to four times greater than in America. That is because taking away guns from the law abiding gives power to the criminals. Criminals will just ignore all gun laws because they don't abide by lawns, hence the name crime. Now, tell me, is gun control worth it?