Priciples are incredibly powerful and valuable. They translate our values in to guidance of how to build something. Values are important, but they don't point to how to do something. For instance writing secure code is important, but simply saying to someone "write more secure code" doesn't help them all that much. Instead you can teach them principles that will guide them, such as least privilege or defence in depth.
They can also be more powerful than processes/tools etc. If someone tells you to use a specific process to do something, but that process doesn't seem to be working, it can be hard for you to know how to change it, you need to understand the rationale behind the process to effectively evolve it.
An example of this would be project management processes. You could implement Scrum without fully understanding how it came to be. Sooner or later though it will need to change, as it won't be effective in all situations, nothing can be. You can do the research, and seek other ways to achieve the same goals. An alternative approach would be LEAN, which doesn't prescribe any particular processes, and focuses on the principles instead. You can evolve a process that suits you based on the principles, but if you simply teach that process, then you are back in the same position.
Vision and values are important, but can be too abstract to guide day-to-day work. Processes and tools are useful, but are too rigid. Principles link the two, allowing people some freedom to innovate, while steering towards the the values and vision. When we find a principle that works, we need to focus on that, and avoid values without implementation, or process without understanding.