I view the von Neumann architecture as more of a reference. When you get down to it, there's so much hardware trickery at play that it isn't easy to cleanly say that any specific computer fits precisely into what Von Neumann was describing. Consider multi-layer caches, CPUs that execute directly out of RAM, mapped IO, or even micro machine code design where the instruction set of the CPU is really an emulated layer on top of a deeper processor, and it's really hard to reconcile these modern machines as a Von Neumann architecture. I'd say that computer design has taken all the pragmatic approaches available. We have had wholesale architecture reboots every ten years or so. Even modern x86 doesn't resemble the original all that much.

However, as a conceptual bundle to teach aspiring computer science students about hardware? It's great!

Requiring that our software be able to simulate a Turing machine has probably held us back more, although that basic abstraction did get us to this point so in no way am I besmirching the work of Dr. Turing.