Speaking of mining the archives of kottke.org, I just found this post that quotes a message board post by Ben Affleck about why he posts his thoughts to the web:
I think there is some responsibility on the part of those folks who benefit from the attentions of some section of the public to be responsive to that group.
It's worth noting that Affleck was one of the first celebrities to post online in a bloggish manner...he'd answer people's questions on his site's message board. (His site is now dead, but a couple of instances of the board were collected by archive.org.)
I remember one post of his in particular (which I can't find on archive.org). Ben was up late, at like 3am, playing Everquest (or maybe Ultima Online?) because he was addicted and couldn't stop. He also mentioned that he was essentially playing the game instead of being in bed with his girlfriend at the time, Gwyneth Paltrow.