Chiplight,
Take care with your interpretation, the two plots at the top do not show the same case, and do not prove the erroneous assumption that ground effect raises the pressure under the helicopter. Those plots (which are quite accurate) do not show the difference between IGE and OGE with the same angle of attack. Note that the deep orange lower plot has more lift, and higher angle of attack than the upper plot, that is why the pressure is higher. In other words, the upper plot shows the greater pressure with ground effect because the lift is greater, since the CHANGE IN CIRCULATION DUE TO THE GROUND contributes to the airfoil's lift. This would cause the helicopter to climb, so the collective would be reduced, equalizing the pressure.
In other words, the pressure under the airfoil, and under the helicopter, is the same in ground effect and out of ground effect, there is NO ground cushion of high pressure air.
The plots do show the circulation that the ground induces, and therefore the way the ground allows you to achieve the same lift with lower collective. Those plots show WHY IGE needs lower angle of attack to achieve the same lift, and that it is not pressure that allows hover IGE to be done at lower power.