That's basically a function, and it might work out if one typical line didn't end up taking up so much space. Expressions still end up more clear and more condensed by such a huge margin it makes nodes look silly in general cases. Houdini is able to make it work but it's all data flow, there are no branches or loops.
This gets in to another problem I didn't mention - branches and loops (not to mention class declarations).
Feeding a function result into another function argument is great, but that was never difficult for expressions anyway. Once you get into branches and loops you have another problem that is a huge problem for nodes.
Ultimately programs don't map to data flow nodes, they are imperative. Certain parts of certain programs will end up mapping very well, but when looking for silver bullets in something that isn't 1:1, you end up hacking it up and forcing a square peg in a round hole to make the dream work.
