I have had many jobs, from supervising a call center to code-monkeying to serving double-skim-milk-decaf-caramel-lattes and training people at all levels in between. The most important thing i have learned about working with and managing people is that all of your employees needs are different, and while fairness is important, acknowledging the various strengths and weaknesses of your staff is essential as is trying to ensure that they all have work environments that promote productivity.
Some people have the ability to tune out background noise and focus themselves on their work. Other people are drawn to every conversation they hear. Some require absolute silence to work productively. Others, like myself, when engaging in code-monkeying or spreadsheet jockeying, find music to be a strong motivator to focus my attention and push me through the grind.
That said, I find vocal music very distracting. If I listen to 'songs', the part of my brain that should be working will start to focus on the lyrics. That's why I prefer instrumental and electronic music. Ideally drum and bass or IDM, or goa. Something with a driving beat, interesting sounds, and a pace that picks up my heart beat, but not mundane enough to shut out my brain. That's a personal preference. Obviously, the same is not true for everyone.
Some people are simply more productive while listening to music. To ignore this is bad management. If allowing the coders to listen to music at work is unfair to the accountants, marketing, and customer support, then perhaps some employees should be given the option to work from home. This is something else that generally increases productivity (of course, not for everyone).