There's a quote by Don Norman that I often reference:
Most technology goes through cycles of development and change in both internal and external complexity. As the technology matures… devices become easier to use, although usually by becoming more complex inside. (from The Invisible Computer)
This provides a succinct description of technology evolution in general, from NASA space modules to hand-held devices. It also applies to enterprise IT infrastructure and applications. Driven by the needs of users who demand smoother experiences and better access to data, enterprise systems are wired together in new ways to accomplish sleight of hand. The problem is the result: messy, ad-hoc solutions without holistic architectural vision. Norman's "easier to use" should apply not only to the end user, but also to the designers, architects, and developers who manage the system.
Ease of use - simplicity - is an illusion. Simplicity is managed complexity. In enterprise IT systems, simplicity results from effective management of architectural layers that interact but remain independent. This allows complexity to be encapsulated where it belongs and reduces the dependencies that result from ad-hoc solutions. The same theory applies to organizational structures, too. Specialists in specific domains (like HR, marketing, IT, sales) combine their functions into a whole system that, when functioning correctly, appears simpler than it is.
Those wishing to make their IT departments and systems simpler need to keep this in mind. Idealized simplicity will never be possible. Certainly, eliminating redundancies and streamlining processes will reduce complexity directly. True simplicity, however, is accomplished when architecture steps in to manage dependencies and identify opportunities for improved design/engineering. If we acknowledge that increased internal complexity is a feature of technology evolution, then we will shift our energies away from elimination of complexity and towards improved management.