For what it's worth, some random thoughts :
1) Just for the record : part of my job implies getting those lines to be hidden/cut/removed/put underground etc. And one thing I can tell you : it takes half an hour and an underpaid subcontractor to put one in place, it takes weeks of efforts for all sorts of people to remove it...
2) I used to think like you, now I would rather see them as interesting compositional tools - all those nice, very straight lines... alternatively, some have very interesting ways of running along the front of a building, etc. It's best, in a sense, in cities with tramways, where you can get amazing patterns of overhead cables crisscrossing the blue sky (photos to follow)
3) you can always Photoshop out those that really ruin the image
4) somehow what buggers me most is not those power lines, but the invasive amount of advertising
5) it's always interesting to travel a bit - as a French, I'm delighted when I go to Italy because they made such a great effort to conserve their inner cities without too much advertisements all over the walls. Also, for such simple things as the bottom of water pipes from the gutters (can't remember the exact technical term in English), they will add an animal shape in wrought iron that will "metamorphose" it into a nice little artisan's work
6) one of the things I intend to do is, conversely, to shoot focusing on precisely those "warts" that stick out - the ubiquitous surveillance cameras for instance. It's also interesting to see how architects, more and more, manage to integrate power lines and such into their work - not hiding it any more, or suffering it, but recognizing it as a constraint that has to be integrated in the general design
7) finally : power lines will probably go the way billboards of fifty years ago did - from a visual nuisance, through decay and degradation, until they remain as a testimony of yesteryear. If you are sensible to it, there can be some beauty on an old building's façade covered in random cables, that you can see as scars on the face of an old soldier ;-)
