It may seem like a mixed blessing now, but without von Neumann architectures computers would not be what they are now. It's an ingenious, and non-obvious idea,

It may seem like a mixed blessing now, but without von Neumann architectures computers would not be what they are now. It's an ingenious, and non-obvious idea, that there should be no essential distinction between "program" and "data" (indeed, Turing machines are based on this idea as well). von Neumann was enormously important in early Computer Science, his contributions cannot be understated. Indeed, Knuth credits him with the one of the most fundamental concepts in all of programming, subroutines (Turing had similar ideas in England around the same time). For more specific examples, von Neumann also came up with the concept of the PRNG, and the first practical algorithm (the "middle square" method). PRNGs are not obvious: before von Neumann, people had only tried generating random numbers using a table or primitive hardware RNGs. He was the one who came up with the idea to generate random numbers using arithmetic methods already present in computers. He also came up with the worlds first practical computer algorithm for sorting, merge sort. There's a huge number of other examples, early CS is riddled with ideas that can from von Neumann.