Negatively judging someone for dressing poorly is as bad as judging someone for dressing well. For that reason, I can't agree completely with either side of the argument expressed in this thread.

With that said, it would be nice to wear a jacket/tie over jeans without feeling overdressed and negatively judged as a "suit" among developers. I agree with the sentiment that developers should wear whatever the fuck they want, but does that not include dressing well?