He's developed a procedural story generator; it doesn't look pretty on the outside, but it's become his life's work and inspired generations of developers.
The visual style of the list may be closer to an academic's webpage (he is a math PhD after all), but for fans of the game, it's a blueprint for a masterpiece.
I personally like the way he designs; write a story then build the game until it could potentially be generated by the game.
This strikes me as a particular, intentional style.
Dwarf fortress is fairly unique in style. I could say it's style is good, but I'd have to describe the game, it's culture, it's development history and how the minimal, perhaps unclean and cludgy style can help weave your imagination into it's narrative.
He could clean up the site, but I think it helps players understand the contract they are getting into by playing this game. A clean website would misrepresent dwarf fortress and it's style.
Or you could wait till someone makes a web page which tracks and sorts all the goals into a readable tree, thus side stepping the issue all together.