It's an interesting idea; my concerns would be:
* People need to admin their servers locally, and it's preferable not to install things like java, flash and silverlight onto servers. These tools are for browsers and internet surfing, they get vulnerabilities, they need patching. I'm a firm believer that the less there is installed on a server, the less there is to go wrong. You might argue that you shouldn't admin locally, but *never* admin locally?
* The MMC was supposed to be the unifying admin interface, and the concept is sound. I'd be wary of having different products administered in different ways.
But I'd say something needs to be done, development of the management UI has fallen behind and it's no longer fully functional. Powershell has great potential, but it's not strong on "rummage around until you find what you need". Everything that's in Powershell should be in the UI, whatever that might be.