Enterprise Manager used to be used to handle moves and changes but with MCD 6 that function was removed. We have some site with it that have been upgraded to 6 and rather then removing it we continue to use it. It can be used to:
1). Be a single point of access for mulitiple systems. That way rather then having to go to different IP addresses to reach the controllers or using pass through you can easily go into Enterprise Manager and you have a list of systems which you can easily access. In addition other products can be put in Enterprise Manager such as a Nupoint so again you have a single "portal".
2) it can be used to collect alarms and send out emails
3) it can be used as a connection to Active Directory.
4). It can be an used in voice quality management as it can collect voice quality stats
5). It can be used for inventory management in that it can collect a list of all phones on the network.
6). It can be used as a backup location.
7). It can be used for software upgrades.
. Think it can also be an element for SDS
Anyway thats some of what it can still be used for. We have some people who have abandoned it because the SWA costs something to keep up to date each year. We have some people still using it for some of the reasons I list above ( and they like it ). So its not necessarily needed becuase you can do most of its functions with something else but usually not a single thing. Hope this helps.