What is a generals job? To win a conflict
What is a politician's job? To control the military.
Of course the military would use everything at their disposal to win a war. It is the politician's job to make sure they are not out of control (killing civilians, using nuclear weapons, provoking 3rd party countries, etc).
If you think MacArthur is a hero in the Korean War, then you've got it all wrong. He may have been a hero in WWII, but his actions were totally reckless in Korea. The US was going to win the Korean War by pushing North Korea back to the Yalu River, but fortunately for the US, MacArthur was in command. He was by nature, a very stubborn hawkish man. He did not take the Chinese threat seriously, and ignored all Chinese warnings. In fact, in a conference with Truman, MacArthur underestimated the Red Army by a factor of 10
on purpose, despite his subordinate generals warning him otherwise. MacArthur claimed that the Red Army possessed no Air Force, and the spy photos by US Recon jets were of fake jets to solidify China's warnings. Nice way of playing down real threats.
Moreover, MacArthur wanted to nuke Chinese cities after their intervention. Im sorry, I know there are a lot of people here who would love to see nukes fly and people die dastardly deaths, but such action would result in WWIII, and the end result is a nuclear war between the US and the USSR. So yes, i fully agree with the politicians to restrain him.
Comment: He was also reckless enough to attack a
Soviet Airfield in Soviet Territory during the war.
Source:
http://www.army.mil/cmh-pg/books/p&d.htm.