Microsoft Internet Explorer 4.0 (also known as Nashville), takes the Microsoft Internet Explorer and integrates it with the shell. The resulting UI is similar to MMC. This was the intent of the Windows administration team from the start– reduce the time needed to learn new tools.
The key difference between MMC and the shell is that MMC is an MDI-based application and offers features that are not needed nor often requested by users for the shell. Managing multiple views is an essential concept in management applications. Another key difference is that MMC treats management applications as documents. This means that as a user you can choose which tools will appear in your environments, and where. There are easily 50+ such tools used to manage Windows NT Server and the BackOffice™ family, without even touching on the even more numerous ISV product offerings. Because of this, tying tools into the Windows shell as namespace extensions is somewhat problematic.
The Windows administration team will continue to follow the shell trends and continue to integrate the MMC UI into the Windows shell. The interfaces provided by MMC are such that these UI changes should have little or no impact on the component Snap-Ins.