After reading the Understanding by Design/Backward Design article, I think you will see how this correlates. You don't demo a kitchen before making plans for what you want the end product to look like.
Just like you want to select what you want students to know and understand for the long term, you want to decide what elements you need to make your kitchen function for you for the long term. As you make a precise drawing of what you want those elements to look like when they hopefully fit together, you plan for your assessment to make sure all the pieces fit together the way you expect. After those steps are done, you demo and build from there in ways (or plan lessons) that will produce what you want that finished kitchen (or final learning) to be.
Focus on the BIG picture, the overarching learning, how the new information can connect for them with information they already have, and standards. The extraneous information that makes it more interesting or gives it more depth may not be the prioritized information you want them to focus on acquiring (understanding), retaining (remembering), and transferring (being able to apply later). That extra information is like the decorations, which are additional touches that make things interesting, but not necessarily part of the original, most important part of the plan. Decorations and additional information can be changed without affecting the primary functionality of the room or basic knowledge. Especially students who have challenges in learning and memory will benefit when information they need to spend time studying and demonstrate learning for is prioritized.