I think the main goal is not to make cloud software the commodity, but rather to make IaaS a commodity, so that there will be multiple vendors of IaaS that are

I think the main goal is not to make cloud software the commodity, but rather to make IaaS a commodity, so that there will be multiple vendors of IaaS that are largely interchangeable. There are today a number of public clouds that run OpenStack, of which HP Cloud and Rackspace Cloud are the two most visible. Because they're all running OpenStack, they are (hopefully) going to be interchangeable commodities. There's still some way to go, but we're much further along than we would be without OpenStack. I believe also that having multiple implementations is not discouraged (but is not the primary goal). The APIs are distinct from the implementation and you are welcome to re-implement them (the docs make a distinction between e.g. the Identity API and the Keystone Identity implementation). I do think it would be interesting to experiment with alternative implementations. Many people, for example, replace the Swift storage component with Ceph, as both support the Openstack Object Storage API.