Washington D.C. is trying to build out a streetcar system, but some residents dislike the idea for apparently aesthetic reasons. The overhead wires will, in their view, cause visual clutter. Matt Yglesias explains why this is dumb.
Recently I was in Prague and Berlin, both of which have lots of trams, and I can't say I was distracted by the visual clutter of the wires. I had the impression instead that they made certain parts of the city seem more alive, which was aesthetically pleasing to me. And they were a good way to get around as a visitor, since you get to see the city as you travel at a relatively slow pace.
In some ways I tend to romanticize public transportation and register my using it extensively as a sign that I am on vacation. (I ride the subway to work, but generally use a car for errands and such.) Unless you use a city's public transportation for a routine commute, it's hard to get a feel for how efficient it is. That said, I was impressed by Berlin's extremely extensive system of trains, trams and buses and the convenience of its honor-system method of ticketing, in which you don't have to pay to board, but need a ticket only in case inspectors ask to see it. I mostly rode the trams, and the whole time it never occurred to me that I once commuted regularly on tram cars, when I lived in West Philadelphia and rode the trolley (which sounds jaunty and old-timey and somehow illegitimate). It was a token-driven system that always felt vaguely like a rip-off.
That Philadelphia seems on the verge of reviving those moribund trolley lines that remain seems like an index of how the city's fortunes have changed (though Atrios points out that such talk has been around for a while). It gives the impression that it is becoming more rather than less dense (which is not apparently the case). And density is ultimately the point of city life. If there are more jobs, residents, and destinations within the city, it makes sense to build out mass transit (that is, public transit that is not buses, which are irreparably stigmatized) that connects the various points and complements the hub-and-spoke regional rail. And then these lines would theoretically make the city more livable. It could help make real the reality it implies.
At one point in the early 20th century, the Philadelphia trolley system was nearly as elaborate as Berlin's trams; my mother used to talk about riding it out to the suburbs to go to Willow Grove Park, which was later demolished to make way for a bowling alley, and then a haute-bourgeois shopping mall. The legend I always heard was that auto companies bought up the trolley car companies and dismantled the tracks to force people into cars, and the associated path dependency helped hollow out cities, enact forced suburbanization and institutionalize the marginalization of the poor who don't own cars.
I don't know if that is a true story, but more generally, it's clear that middle-class Americans are now too committed to car culture to ever support European-style urbanism. For instance, zoning regulations in many cities seem to privilege parking spaces over buildings themselves, a reflection of the constituency they serve. And home ownership, sadly, is still the American Dream, no matter how isolating or unsustainable or anti-egalitarian it proves to be. (Try renting your way into a good public-school system.) Apparently, being American means avoiding neighborliness on anything but one's own terms.