I think Brian has the right approach, but for a different reason.  Part of the process of an upgrade is the testing that MUST occur for all of your applications that use the database.  Testing against the huge set of features in the SQL Server 2005 release is going to be a mammoth task that, frankly, most companies are going to gloss over or skip altogther.  Having a smaller feature set allows that testing to be much more concise and manageable by an already downsized and overworked database admin and development staff.

MW