On the one hand, this is delivering the utmost of simplification to the users but under the hood, the same complexity remains. It is a different view from two opposite sides of the solution.
I completly get this, and like I said there are few people who will say that Fiori was a bad call. It wasn't, SAP needs simpler UIs for people that do very specific and repetitive tasks and don't need all the complexity of a VA01. But this is from a user perspective, like you say the complexity/flexibility is still there underneath the hood, available for those complicated processes.
But the "Simpler" message isn't directed at end users, it's directed at decision makers, CIOs, which are much more concerned about TCO and Capex that comes with a SAP, therefore I completly agree that the risk is that decision makers "won't accept the underlying complexity". On the other hand I also believe that there is a actual risk of "dumbing down" interpretation.