What operational benefits come from ‘layering’ VAAs?

There can be a lot of reuse – like SOA or Lego building blocks.  It allows for an object-oriented approach to deploying applications.  And you can separate out concerns along organizational lines.  One gold MySQL VAA could have tons of different application VAAs on top – powerful and flexible.  One group could be responsible for maintaining the MySQL VAA and another group the Apache Web Server VAA.  Each group can make the changes independently of each other. 

Instead of lining up in order with installation media, each group simply takes care of their own VAA.  When the VAAs that make up the application stack are run in context, the result is one running system – updated, current.  The fact that each group does their own VAA independently puts fences with clear accountability amongst organizations.