There have been several industry initiatives over the years to develop a model for managing systems and devices that would be robust enough to meet the needs of most vendors. Several protocols and frameworks have been developed to address the problem. The Simple Network Management Protocol (SNMP) is probably the most notable, but is pretty simple in its implementation and does not provide many features most vendors need for a single management framework.
The Distributed Management Task Force (DTMF) was created in the early 1990s to address the management framework problem. They developed the Web Based Enterprise Management (WBEM) standard, which attempts to unify the management frameworks utilizing web technologies. As part of the WBEM standard, they also created the Common Information Model (CIM), which is the language used for describing management data in an object-oriented way. The WBEM/CIM standards have garnered a lot of industry support in recent years and provide the basis for WMI.
For more information on WBEM/CIM, check out the DMTF website: http://www.dmtf.org.