I posted this over on urbanplanet in regards to the bridge, so thought I might as well post it here too! Sorry if this is repeat reading for anyone. haha
That thing is beautiful and, in my opinion, well worth the price tag. I agree that at first glance, this might seem a silly expense merely to save 600 feet of walking, but although one can access The Gulch on foot via Demonbreun, there is still a major physical separation brought on by the railroad tracks and, more notably, a major physiological separation for pedestrians that might hinder them from making the journey on foot. This bridge, in physical terms, may only lop a few hundred feet off of the walk, but it creates a sort of 'grand entrance' to The Gulch, which is huge in terms of making the walk exponentially more inviting and feel more worth the trip.
Beyond that, since this bridge will be visible from afar, it creates interest in people (say, tourists or conventioneers) that aren't all that aware of The Gulch and what it has to offer. After a convention, people might funnel out of the MCC in the mood for a night out, see the bright shining beacon that is this bridge, and end up wandering in that direction rather than making a B-line for Broadway. To me, creating a great pedestrian experience at street level is worth every penny a city can afford to pump into it. Sure, technically, people can walk down Demonbreun, past some dark alleys and empty lots, but if Nashville as a city is going to rely on that connection point to get people into The Gulch, then they'll have to get used to being disappointed by the numbers of people actually making the journey. The island paradise might be visible from the shore, but if you have to swim through shark-infested waters to get there, most people aren't going to feel it's worth it to make the trip.