Hi,
That's halfway the case.
We indeed did not adapt the wishlist system to allow for guest wishlists.
However, after talking with people interested with that idea, it appear that they are a simpler need of just allowing guest users to like the products and have a list of their liked products. And not something more complex with sharing, and multiple instances.
So we developed a plugin to do that:
www.hikashop.com/marketplace/product/155-product-like-btn.html
With it, you can have a list of liked products and easily add / remove the products from it, display it, and it works with guest users too.
There is however no sharing feature with it. That could be something that could be quite easily added to the plugin with some small adjustments compared to allowing guest mode for wishlists.