In addition to the reasons given here, I'd say that as far as bang-for-buck in terms of visual realism goes, power lines are pretty effective. They look complex

In addition to the reasons given here, I'd say that as far as bang-for-buck in terms of visual realism goes, power lines are pretty effective. They look complex but are quite fast to draw with line tools or model in a 3d package and usually can be represented with minimal shading. Creating the impression of modern urban landscapes is largely a question of creating very detail-dense images, and power lines are a pretty cheap way to add a lot of small detail.