wormholewizards: I have beaten both games once. Is there any other reason or motivation for second playthrough? Just for the record I enjoyed my first ride, mainly because of the writing.
I like to play any game I like more than once, so I may not be the best person to weigh in on this. However, just based on the elements of the first game, I could see there being a reason to play the game again on a harder difficulty since some manuscript pages can only be found on (I think) the hardest difficulty. If you don't want the extra difficulty and you are like me and don't try to do every single thing on a first playthrough, you wouldn't even have to bump the difficulty up to experience more of the game. I don't think I've ever found all of the manuscript pages available on the Normal difficulty. Also, there are the collectible thermoses, though whether or not they are worth playing the game all over again for isn't for me to say.