As a framework, Unity can be used to build anything from small applications that require only a handful of sound effects and a single background track to huge role-playing games that need millions of lines of spoken dialog, music tracks, and ambient sound effects. Regardless of the actual scope of the application, audio files are often a significant contributor to the application size after it is built (sometimes called its disk footprint). Moreover, many developers are surprised to find that runtime audio processing can turn into a significant source of CPU and memory consumption.
Audio is often neglected on both sides of the gaming industry: developers tend not to commit many resources to it until the last minute and users rarely pay attention to it. Nobody notices when audio is handled well, but we all know what lousy audio sounds like—it's instantly recognizable...