VMware explains that they are responding to customer “demand for powerful OpenStack APIs to their developers” with their OpenStack product. In other words, what OpenStack provides is a nice set of developer APIs, and if developers want that, VMware will provide it for them on top of their existing infrastructure.
OpenStack APIs are not oriented at developers. Developers building apps in the cloud don’t want to think about managing underlying infrastructure, managing storage, or configuring network topologies. Instead, they want to build microservices or mobile interfaces or analytics capabilities. IaaS clouds like OpenStack just provide a building block on which development and application platforms sit. This is why so many developers love building apps with technologies like OpenShift or FeedHenry, which can run on top of OpenStack.
OpenStack APIs are for cloud administrators who want to offer public-cloud-like infrastructure services in their own datacenter. And, cloud administrators have quite different interests for cloud infrastructure not only from developers but from virtualization administrators as well. In particular, cloud administrators care about agile operational management and horizontal scale and elasticity.