I've gone through the same transformation but I think you aren't appreciating the larger picture. Having the ability to specify both compile time and runtime invariants are both useful features. Java is good at expressing invariants around datatypes that looks like hardware data storage but it is so restrictive around interfaces that it is easy to paint yourself in a corner. Since Java was the mainstream typed language, people saw what could be done in languages like Python without such enforced rails, that many people decided the expressiveness was worth the tradeoff. I think Java 8 is much better about the tradeoff, but ultimately I think we haven't invented the system for expressing invariants in a language that makes the best tradeoffs between expressiveness and flexibility.