Why would it be so bad to cut US military spending?

Republicans in the House of congress are now try avoid the mandatory spending cuts to the military that were part of the deal struck for last years increase of the debt ceiling. What I don't understand is why it would be so bad to cut the US defense budget.

According to Wikipedia the US spent roughly $711 billion dollars on the military in 2011. Not only is this the highest percentage of GDP of any larger world economy except for Saudi Arabia but it is also almost half of all military spending in the world (The total is $1630 billion). Also if we look at the top 15 list of countries that spend the most on the military only Russia and China are not either members of NATO or staunch allies of the US. The number two on the list China spends less than 20% of what the US spends on the military. Would it really be so bad if we only outspend every country in the world with just 100% instead of 400%? That change would save us at least $400 billion a year. Sure, we wouldn't be able to run around the world starting wars all the time like we are doing now, but would that really be so bad?

Given that I know this will not come to pass because the US will never willfully give up it's current military hegemony I also like this article in the Wall Street Journal who talks about business leaders meeting with congress to impress on them the importance of actually starting to talk to the people on the other side of the isle and figure out a solution to this problem that will probably be hard to swallow for either side since it will probably need to contain both hard budget cuts and raised taxes.