Standards (in particular interface standards) are essential to ensure that LibreCube Elements are compatible to each other. Without standardization adapters would be needed to fit the elements together and that would not be economical. Just think about the many different power plug formats used all over the world - you have to bring along a clunky power adapter whenever you travel abroad!
It is not that the engineering world is short of standards. But usually standards are hard to read and it is not easy to decide which standard to follow. Therefore, LibreCube has defined a clear policy on what standards to choose from. The criteria are that they must be: openly available (downloadable from internet), free of costs, and preferably based on space heritage. Luckily there exists two major organizations that publish standards that fall perfectly in this category: the European Cooperation for Space Standardization (ECSS) and the Consultative Committee for Space Data Systems (CCSDS).
A review of ECSS and CCSDS standards with potential application for CubeSat (and hence LibreCube elements) has been produced. You can find it here: https://bitbucket.org/artur-scholz/cubesat-standards-handbook.