Now Zork belongs to MS. Release it under MIT and everyone would win a great history of gaming (and the right to create new histories in the Zorkverse without worrying). Spiritwrak it's a good example. In case of anyone says "text adventures have no future"... the folk lore from a distant past made Disney rich. The Arturian legends plus some samurai touches set into a futuristic space made George Lucas and Lucasfilms…
I'm not sure if they'd be willing to do so for the game assets (the room/item descriptions/etc) – it would remove one of the main legal barriers to a competitor creating their own game set in the Zork universe. The Fortran 77 version of Zork has long been available under a "non-commercial use only" license, so they might be willing to release the game assets under such a license too (or maybe a more modern equivalent such as CC-BY-NC or CC-BY-NC-SA)