This is an interesting observation, but I don't think internal consistency is an appropriate measure for the "goodness" of a value system. It says nothing about whether entities with a particular value system are capable of forming stable societies; I wouldn't accept any value system that lead to always choosing D in the iterated prisoner's dilemma as good, for example, no matter how internally consistent. And a paperclippers's value system has a very hbigh degree of internal consistency.

In fact, I have a hard time accepting any quality measure over value systems which doesn't include degree of correlation with my own, or at least with most of the major, non-controversial points thereof.