The advantage in interface design, like military commands, is the command and control structure. MM is open source, with a great many contributors of varying capability and available time. The project leads do a good job of keeping the various parts generally in line with each other but there is still that free-flowing design element. Compare that to a conventional business model with design patterns, dedicated interface designers, project goals, strict guidelines on what what the UI should/should not look like. The end result will be much more highly polished and refined, but could lack a number of finer details that open-source programmers would "adopt" as their own contributions. Each method of development has its advantages and drawbacks.