The wiki format provides a wide range of benefits for a project like this.
First is the ability to collaborate. Since metaculture is an emergent system of thought, there are millions of people with their own knowledge and perspective about each subject. The wiki format allows them all to contribute if they have something to add.
People also get things wrong, and scientific advancement enhances and replaces old ideas as our knowledge about them expands. Wiki will allow anyone to point out and correct factual errors, or update pages on any subject that has become obsolete. A static writing would forever enshrine those obsolete ideas until it reads like a 50 year old science textbook.
The wiki format will allow those additions and revisions to continue in perpetuity. If the goal of metaculture is to create a system of thought that can supplant the ones that have stood for the last 2000 years, it needs to allow for all the changes that will come in the next 2000 years. This cannot be accomplished with a static writing format. We can barely imagine what the next 100 years of scientific advancement will bring, much less the next 1000.
The non-linear reading format wiki provides has two key advantages. Human thought itself is non-linear, constantly veering off on tangents as the conceptual associations we make focus our attention on new ideas. Each person comes to it with their own knowledge and ignorance on each subject. If an article mentions Maslow's hierarchy of needs for instance, you may already know all about this subject or you may have never heard of it. The wiki format allows you to follow that link and learn more about it if necessary, or continue reading if you are already familiar with the subject.
This allows each article to be written much more concisely than it could be in a linear format. In a book it is necessary to dedicate time, energy and space to any concept that the reader is likely to be unfamiliar with. Any avid reader of popular science and philosophy is familiar with the tedium of having the same common concepts explained again and again in every book they read because of the possibility that another reader may be learning about the subject for the first time. The wiki format replaces these redundant explanations with a single link that the reader can follow if needed.
As the wiki grows and changes over time, the common thread will be a single point of view that unifies all of these concepts. That science and the scientific method are the tools we use to understand the universe, that the universe can and should be understood holistically, and the importance of unifying the disparate areas of human knowledge into a single conceptual framework to enhance the understanding and meaning we are able to derive from it.