I think you are right and I would add Turing incompleteness to that list. If your problem isn't Turing complete, then a complete language is actually probably n

I think you are right and I would add Turing incompleteness to that list. If your problem isn't Turing complete, then a complete language is actually probably not the best tool for the job. Incomplete languages actually give you more power than in a Turing complete language in that case. Completeness is a feature of a language and like all features there are tradeoffs. The ability to express more kinds of problems comes with the cost of not being able to leverage the contours of a particular problem (e.g. monotonic data, no cycles) to increase things like speed, debuggability, parallelization. This can enable cool features things that seem completely out of reach today. e.g. rewinding the state of your program to debug production errors. Modifying programs as they're running. Automatically parallelizing computations across an arbitrary number of cores. The ability to query the provenance of any variable in your program. Datalog's incompleteness for example allows it to resolve queries faster than a complete language like Prolog due to the simplifying inferences it can make about the code.