No one is saying they are hiding anything with the photos. Actually from the photos you can already tell of some interesting features like the lack of an A pillar and how the same piece of glass essentially goes over your head like you would in an airplane. We also know of the cooled seats and I'm sure the cooled seats will also be offered in the Model S.
What some are saying is that the Model X will have more advanced features that they are not divulging now mostly because they don't want it to affect current Model S sales.
It is almost guaranteed that the Model X will have ver. 2.0 Autopilot sensors and that alone is a big deal. Also I would be completely shocked a modern SUV like the Model X would lack 360 degree view as I'm sure that's a feature many owners with families will appreciate when they park and maneuver what is a quite large vehicle. The Model X might also have a better audio system and possibly a faster CPU as well.
The bottom line is they are keeping a bunch of toys and goodies for the reveal so they can make a big splash. It might take months for these new features to eventually appear in the Model S but sooner or later they well.
Agree with you on all points ----- well said.