This is explained in the FAQ
Thank you for the reply. I should have mentioned that I had already read the FAQ but I wished to ask for more details. These files are reasonably simple to re-write under a new license (excepting perhaps RegExp.java) and whether there was a reason (apart from lack of time) why this wasn't already done.
If there is no particular reason and it will be done in the future when the devs get around to it, then I'll close this query.
There's no reason why the files are still there other than we haven't got around to rewriting/replacing them yet