Many classification techniques are more sophisticated than Naive Bayes, but that doesn’t necessarily make them better. As always, it’s about finding the right tool for the job. For this application (mostly a text classification problem), Naive Bayes performs great and has fewer moving parts than the alternatives. Also, gathering great training data and selecting the right features are challenges in their own right and probably affected the final user experience much more than the choice of classification algorithm.

We currently don’t plan to share the recipe training data, but we’d definitely like to have developers build other kinds of classifiers over time, and the “classifications” field in the API was added with this in mind.