Why are images used to indent comments?
TallGuyShort: I think one of the main reasons some web design techniques are "bad" are because they don't sufficiently separate layout and design from content. The problem is - on a site like HN, you're primarily catering to a crowd that just wants a really simple, straightforward design that's easy to use to fast. We get that with a 1-pixel image. Adding css could potentially throw more complexity into the mix.