The goodness of license is not determined how developers understand the text. The goodness of license is determined how it is interpreted in the courts. There are good websites who explain and different licenses to developers or help them to choose. If still not clear, ask software lawyer to explain details. https://choosealicense.com/
Analogy with code. Code should be simple and easy to understand, but it's more important to execute correctly, including all special cases. The microprocessor or interpreter is the "court" for code writing. The good license covers all cases and uses phraseology with well-defined meanings and existing interpretations. Legal contracts often have an ambiguity that is reduced when it is tested in court. The more it is tested, the better you know what it means.
GPL and MPL are very different types of copyleft. MPL is weak copyleft bound to individual files. It's simple because it does simple things. If that's enough go for it. But don't complain when someone uses it according to the permissions the license gives.