Why? There are many different organisations including universities companies and so on that want to use the open cores and many of them either develop new stuff

Why? There are many different organisations including universities companies and so on that want to use the open cores and many of them either develop new stuff fully open or partly open. Also, the chips can be both, you can have open source implementations and close source implementations and when you are building a chip you have to make the choices just as in software.