Portal Technology : Glass or Optics?

Many vendors describe portal software as a glass through which you can view your applications.  I’m still to be won over that portalising applications is the best way to serve them to users.  I’m also increasingly annoyed about the level of version rigidity between portals and those applications.  It is increasingly apparent to me that the portal isn’t in fact a glass but a hall of optics which select a particular colour and transmit that colour.  So for most portals each application would be a colour.  The application and portlets would be the optics and the end result is you see many colours (or applications at the portal).  Change the version of the application, and hence its colour, and all of a sudden you no longer see that application on the portal.  This is so constraining it is beyond belief.  Simple upgrade projects turn into complex programmes.  To upgrade application to version z you need to update the portal to version y.  Moving the portal to version y prevents application a,b, and c from working.  Just a bit of a rant, especially when in some cases the portal and applications are from the same vendor.