The reason you call the Cold War the Cold War and not World War 3 is because of what stopped the system of wars you refer to, and what immediately ended the second world war: nuclear weapons. Nuclear weapons prevent countries from militarily exerting influence against another nuclear nation. Nuclear weapons are the great equalizer of power. Pakistan was harboring Osama Bin Laden next to a military related facility - a man we destroyed two countries seeking, one under completely false pretenses. Yet when we finally found him, in Pakistan, our response was a silent and rapid in and out followed by mostly token gestures. Iraq and Afghanistan did not have nuclear weapons. Pakistan does.
All our current system of relations has done is turn US into the world's final word on everything. This creates more of an autocratic than a democratic system of world relations. That Saudi Arabia sits on UN human rights council, chairing their advisory committee (which chooses appointed 'independent experts') speaks to how functioning our international institutions are. They are a little more than a proxy for US influence. I do not think any single government should have such a unilateral influence on the happenings of the world.