I think he's got a point that Von Neumann machines get trashed a lot by people who have no better alternative. After designing a processor in a senior level computer architecture class, I think the Von Neumann machine really is the best organization given your building blocks are binary logic gates. Also, a lot of work has been done on instruction level parallelism, caches, and branch prediction that keep the whole processor humming. Hardware is very expensive to design and build, so it's economical to build to a general purpose and widely used instruction set architecture and then optimize that as much as possible. The next best thing is probably massively parallel architectures, but the compilers and programming languages to support those are just not there yet and there is so much code written sequentially. Perhaps when we have some crazy new medium to build processors on (think analog neural nets or quantum computers), a better architecture for those mediums will supplant Von Neumann's.