Swapping to an entirely new license rather than adding one sentence to the existing one is not simpler either in terms of linguistics or getting approval from their army of lawyers.
It would require getting all past contributors _and_ the current copyright owner to agree. Normally I'd agree that getting all past contributors to agree is the hard part, but the copyright owner here is Oracle. I'd have more confidence in getting the rest of the contributors to agree to a license in Pig Latin than getting Oracle to make literally any change to the license for this.
I think some projects have done that in the past, but probably none where a big company owns the copyright to most of the code.