The back- story:
Once upon a time, when Reporting Services 2005 was just barely gold, one was able to use a “Select All” feature with multi-valued parameters. At first glance, it was a handsome, strapping feature.
After a time, it became apparent that “Select All” wasn’t such a hero after all. In certain scenarios, it could impact Analysis Services performance negatively. “Select All” was subsequently banished from the product in SP1 (http://blogs.msdn.com/bwelcker/archive/2006/08/14/700189.aspx).
However, not long after “Select All” was booted, quite a few users were…unhappy. The petitioned the Reporting Services crew to bring their knight in shining armor back from exile. They were such a persistent bunch, the feature reappeared in SP2.
Now, once again folks are asking if they can turn off “Select All” in SP2, and the answer is … No, you can’t (cue up “Circle of life” music).