Apparently, Canonical wants to the Ubuntu Software Center to take its place.
There are ups and downs to this. Synaptic is fairly daunting for new users to learn, and is not very GUI friendly. On the other hand, Synaptic does has several features that the Ubuntu Software Center does not (yet) have. So it’s a step backwards in functionality.
But, like the decision to remove the GIMP, you’ll still be able to install Synaptic from the Ubuntu repositories. So long as that ability’s still there, I don’t think it matters so much what comes on the Ubuntu initial install disc.