Maybe it's not a case of simplification over time, but of abstraction: the gradual comprehension that, say, canis in canis virum mordet ("the dog bites the man"

Maybe it's not a case of simplification over time, but of abstraction: the gradual comprehension that, say, canis in canis virum mordet ("the dog bites the man") and canem in vir canem mordet ("the man bites the dog") are not two distinct (if related) concepts, but the same concept performing different roles.