While I appreciate the premise that the ideas belong to NO one, let me lay out why I think copyright (or any other right that has legality) are necessary (and completely acknowledging the fact that ideas are indeed a gift from Omnipresence)...

Take the idea of land/buildings. What happens if we did not have a system in place to document who owns what, there will be chaos and only POWERFUL get to live wherever they choose to. Those who are weak or hard working without power will be thrown without shelter. It will be an utter failure of civilization.

Why did I choose land and buildings as an example? Because this land was a gift to us by the Nature/Ominscence and buildings are what we build on them. IF we did not own the right to piece of land or building - do you think we would live in a sane civilization?

What is an idea, it is the land that nature gifts us. What we build with that idea becomes a tangible structure that takes birth for others to see, use and enjoy. If there is no right to this - then those that will benefit the most are those that have the power to exploit.

I like your premise and I wouldn't mind being part of a Utopia where all can live in a shared community but unfortunately we are not that civilized yet!