A world with an America unchallenged by anything is also dangerous. Thats how we get a 20 year war with countless innocent lives destroyed, entire regions destabilized and a host of other terrible situations. The country is just that: a country, a collection of humans with human flaws. America at its best was when it was trying to prove the effectiveness of its system over others day in and day out because it was being challenged. Thats how we got a lot of the freedoms and benefits that we have now.