Popular works regularly mine the (public domain) past. Disney animated movies like Cinderella did so. Seth Grahame-Smith did so with Pride and Prejudice and Zombies. and so on. That is literally the benefit of copyright expiration, that other people can utilize and transform a published work.

Agree. There's some impressively modern looking output, however. Quite elegant. Seems like a relevant place to repeat a quote I collected:

There was a romantic tradition, in this country at least, of the drifter Typesetters, who were good enough at the craft to find work wherever they traveled. They'd work in one town until they wanted a change and then drift on. They had a reputation for being well read, occasionally hard drinking, strong union men who enjoyed an independence particularly rare in the 19th century. - Clark E. Coffee (founder of Graphion, a phototypesetting company in SF)

I actually don't mind it. They did the work of generating the font files from the public domain works, and you're paying them for that work.

If someone took a close-up photo of a statue's stone texture, I don't see any problem with someone editing the photo and selling it as part of a texture pack for 3d modeling. I feel like what was done here involved a roughly similar amount of transformation. I agree that the right thing to do is attribute the source, though.