A Great Cover Letter Is All That's Missing
A cover letter tells a lot about the candidate that does not show up on the resume. Your ability to express yourself in written language, the presence of coherent thought, your motivation for selecting this company, the degree of value you seek to bring to the company and so on. Companies are looking for extraordinary people...extra-ordinary...beyond ordinary! What distinguishes you from everyone else in the waiting room?
The cover letter says a lot. Instead of boring interviewers with cover letters they have seen so many times that they can recite them word-for-word, it would better to identify common problems that you know they are encountering and state your intended plan of action to address those issues. While you could not really know the specifics of their problems, there are generic problems that all organizations are wrestling with like communication issues, low morale, inefficiency, delays, etc.
Light up your cover letter with creative solutions to their ills. They don't have to be specific but at least they show that you are bringing something to the table other than a nice personality.