If there is a large network building owners will happily install and maintain them. In some places the expensive store fronts are on the second floor where all the people are: they take those cat walks from building to building without putting a coat on.

Maybe in some areas it may work but for most cities and many places in those cities it just won't work.

Like any system you need a critical mass of infrastructure before it takes off. Is it worth it for your situation is always a valid question.