Nature designs with recipes, humans design with blueprints. DNA is far more like a recipe than the blueprints which form the basis of architectural design.
If you baked a fruit cake according to a blueprint, it would say something like: position 83 raisins at 1 inch intervals in a 10 x 6 x 3 grid. Every fruit cake would look the same and the results would be clinical and unnatural. This is the way cities are designed, from the New York city grid to the boulevards of Paris. Where they look different, such as a medieval town, the result is happy accident, over time, or implementation by craftsmen on the ground rather than the work of architects or masterplanners.
Conversely, when you bake a cake according to a recipe, every one looks slightly different, because of tiny environmental differences and the cook can adapt the recipe to improve it. The makers are designers and the recipe can be passed on and evolve.
The difference between a recipe and a blueprint is that a recipe adapts to the environment and allows people who make things based on it, to adapt and improve it. Recipes also have the benefit of requiring less information than a blueprint.
Until recently it was very difficult to formally implement recipes as an alternative to blueprint style design. This was because recipes are simple instructions which often need to be iterated a very large number of times to achieve the desired rich complexity of nature and until computers this was not possible. The repetition of a recipe instruction is an algorithm.
Early design algorithms were based on feeding the results of very simple equations back into the equation over an over again. They resulted in the infinite complexity of fractals that reflected natural forms but from an aesthetic point of view they were not used for producing much beyond lurid t-shirt designs.
Some simpler design tasks such as Internet applications have evolved a hybrid approach that has some recipe elements through the iteration of design alternatives with A/B testing. Ironically the recipe design is viewed as something less creative, the realm of focus groups and marketing, by missing the point that if a series of rules for a suite of A/B testing was treated as a creative design exercise, then this would be like designing a recipe.
Until recently, recipe based design has not been understood well enough to build something as complex as a city from a few simple iterated rules. Now, however, I believe we could create a city that had the richness, variation and environmental sensitivity of an organic design built over hundreds of years.
An algorithmic approach would be a wonderful thing for a new city of the future or even for an existing one, bringing residents, planners and architects together. It would produce a much more human environment by having detail at every scale from choosing a few simple rules to iterate on.