Effort and Equipment. If a game's story is fully written before the first release it will be faster but many devs see the product after a couple of years and have to go back and fix the visuals of past chapters so they look as good as the stuff they are producing now.
Now and Then with updated visuals would be amazing. The world and story are top notch and the content is plentiful. Also, another game in that universe would be fun to play.