That high pressure causes some odd taste notes and it would cause channeling in the puck. Not to mention all sort of other issues which start already at ~11 bars.
I found this article interesting because they talk about the complexity of espresso as being characteristic of a mix of extractions at different pressures. This is apparently different than the model they came up with to brew the perfect espresso. But they also note that 9-11 bars is too high and go as low as 7. Fascinating.
I strongly believe that the Nespresso was designed to solve/create a problem to fit their business model.
In this order: Proprietary, good margin, small foot print (pods and extraction unit), easy to use, disposable.