[DiogenesKynikos]

The KJV version of the Ten Commandments is still easily comprehensible. You only need to know a few archaic constructions ("spake" instead of "spoke," "thou" instead of "you"), which most native speakers of English are probably reasonably familiar with.

Looking at the Luther Bible, it has a similar number of archaic constructs as the KJV. For example, it uses archaic forms of the genitive case extensively (compare Luther's "der Väter Missetat" with the modern German equivalent, "die Missetat der Väter").

The reason people like these old translations, in my view, is that the slightly archaic language separates them from the common language we use in our everyday lives. That separates the book from the "profane" or mundane everyday world, and makes it something special. Even as a cynical atheist, I appreciate the feeling that this sort of slightly archaic language creates.

1. The Ten Commandments in the Luther Bible: https://www.bibel-online.net/buch/luther_1912/2_mose/20/#1