If there is no payment system, then resources are guaranteed to be oversubscribed and exhausted if they are at all interesting. In the Iain M Banks Culture, that works, but we're not there yet.
The best parts of my life are already voluntary, cooperative, and social - people working together to make things better for each other. I want more of this, not less. Micropayments just drag the old way into the new. Why waste our time on that? Let's build the future we actually want to live in.