This is a statement on the aims goals and mission of the foundation, once the foundation is incorporated this statement can't be changed, A well written charter will give the community and SUSE comfort that the board of the foundation can't go off and start doing something radically different. For example it could state that the foundation supports free and open software / (hardware?) projects and that all the code / designs must be publicly accessible. At the same time we need to be careful not to limit ourselves to certain technologies etc, because who knows if Linux for example will be the best kernel in 50 years.
Unlike many other forms of foundation setting up a Stiftung requires 50k as a seed fund. This is something previous boards have also discussed with SUSE.
Stiftung's don't have a predefined governance structure in terms of the board makeup and how they are appointed which gives us significant freedom in this area. However there are quite strict rules around keeping financial accounts and yearly reporting to the point where it is unreasonable to be able to expect volunteers to do this work.