For one thing, it's apparent by now that vendors of at least one kind of IT management system -- so-called IT automation platforms -- are intent only on servers. (See IT Automation Bypasses Storage.) Vendors like BladeLogic are addressing the needs of customers in large enterprises where storage and servers are separate fiefdoms. Server managers don't want contact with underlying storage complexities, and to some extent, storage managers are protective of their bailiwick and distrustful of attempts by "outsiders" to automate it.
On top of this, the many attempts to standardize IT management itself have largely failed. Sure, years back SNMP became a de facto way for devices and software to report their basic functions to a central console. But over time, efforts to build on this have simply evaporated. The truth of the matter is that big vendors just don't want heterogeneous management standards, period.
Readers of a certain age, I ask: Remember DME? WBEM? CMIP? NMF? For more than a decade, lots of effort and money were thrown into efforts toward a standard interface for computers and networking gear. But products like HP OpenView, CA Unicenter, and IBM Tivoli managed to stay largely untouched by all of them, despite appearing supportive.