Addy -
MattM makes a lot of points, way too many to address with comment replies! Some of these points are things we are considering how best to improve for future updates; some of them are things that were considered and rejected for the RTM because we believed them to be less important (this constitutes some portion of the list provided in the blog post).
There were a number of reasons to remove the AD integration. Some of them involved usability, and some were technical in nature. Due to the change to powershell infrastructure, the old extensions could not simply have been ported forward, of course (plus there are a number of old things removed and new things added to Exchange 2007 that would have to be handled). And please also consider that even if it was somehow just as simple as bringing forward the old ADUC extensions unchanged, you'd lose the ability to do the cmdlet-based recipient management using powershell. We decided that we could cover a LOT more of the customer requirements for a LOT more of the customers if we instrumented recipient management with powershell to match the rest of the management infrastructure and integrated recipient management into the shell and console directly.
Thanks to all for the continuing comments and please keep them coming! If you'd prefer to email your comments to me directly, you're welcome to pass along your comments that way also: evand-at@-microsoft.com
Evan