I'm not sure if you are joking, but language is highly political. You could say that language is the root of cultural, and thus national and ethnic, identity.

Language domination tends to follow political, trade, and economic domination. The "lingua franca" of Europe used to be, as the phrase implies, French. Before that was bastard Latin, after that it was German. More people speak Spanish than English in the New World, and Brazillian is a close third.

The problem with suggesting a default language is that you are also implying worldwide domination. It's not usually a welcome idea. :)

There is a joke about that: air traffic control frequencies are shared, for obvious reasons. Once a Lufthansa flight was coming into Berlin. The pilot asked for clearance in German. The tower responded that he must use English, as that is the rule. The pilot responded: "Why? I am a German, flying a German plane to a German airport. Why must I speak English?" Another pilot cut in-- "because you lost the bloody war!"

This is actually true; if you don't trust the pilots of a former enemy, a good way to keep tabs on them is to make them use your language on the radio. QED.