It's a great idea in theory, but then who funds it? And if they create a new technology, who gets access to the patents? And if they send a person into space, how do they decide who to send?

If they make a new technology and they decide that it just belongs to "humanity", and make it royalty-free, then whoever funded the program suddenly gets angry that they didn't get a return on their investment. If they only give the patent to those who contributed money, then "that's not fair because it's supposed to be a global effort." There's a thousand counter-arguments along every step, just because the nations are so far apart economically; what might seem fair to some would seem despotic to others, and what might seem fair to others might seem communistic to some, and so on. Eventually some nations would officially denounce it, and say "We'll just make our own!"

I agree that it's a good idea, I just think that there would need to be a lot of red tape and diplomacy involved.