These are nonrival goods -- as many people can use and enjoy them as want to with no hindrance or loss to any. When there is plenty for everyone, why should any have a right to impose restrictions on others? The only plausible reason is a collective one: that we can in practice (by stimulating production) get a better functioning economy.

Living for others' sake is what being human is largely about, it is what cooperative systems like economies are about -- which are critical for us to live well. By maximising our costless use of nonrival goods we all gain.