Fakery?

[oshfdk]

I'm not sure VMS was a commercial project, exactly for the reasons you listed. I agree with Linda that it's much easier to see it in the context of an experimental, personal or community (cult, sect) creation.

The VM may be put together like a pocket reference book, but it makes little sense to be one. An encrypted volume means that the key is kept elsewhere and the two need to be brought together, at least once. I would think that once decrypted, the owner would put in readable margin notes. That way, even if the book was taken and the key left at home, there would be something to jog the memory.

I don't think I understand why your interpretation of the "key" is so specific. Depending on how the manuscript is encoded, "the key" could be anything from a big volume of codes or a specific device to a very basic principle that is easy to remember.

For example, the following is a simple way of encoding a text of any length in almost any language or script. If I'm not mistaken, something similar was mentioned in Traicté des chiffres ou Secrètes by Blaise Vigenère (1586).

The ciphertext:

AGH BH CADEDG CADFDGIG AG CBDFHG CBDHIF BAHFB CAGIC ABDHGA

The key is the following block of letters:

ABC
DEF
GHI

Each ciphertext word is a plaintext letter, encoded as a shape. You put your pen over the key block at the point indicated by the first letter of the ciphertext word and then trace straight lines through the points in the sequence of letters until you hit a ciphertext space. Then you start tracing the next letter. 

For example, A-G-H is an L shape staring from A, moving down to G and then to the right to H. There are several possible ways of encoding each letter by shifting of modifying the shape or scale, you can encode L as A-G-I, B-E-F, B-H-I, etc. 

If we extend the key horizontally or vertically, we can have a verbose cipher that would be fairly hard to break, unless you know the underlying principle and the key block. However, remembering/reconstructing the key is very easy, if it's as simple as above, you should only remember that it's 3x3 characters and they are written alphabetically in the natural left to right, top to bottom direction. With this cipher you can represent letters of various alphabets and arbitrary symbols, especially if you use a larger 4x4 or 5x5 block. You certainly have no problem with "leaving the key at home" or explaining the principle to anyone in under 5 minutes, but without the explanation the cipher is not very easy to break.

If you want to test how hard it is, here is a simple ciphertext encoded in a very similar fashion using exactly the same 3x3 block with the same letters ordered in the same way (I'm making the task as easy as possible), but with a small twist that is just as easy to explain and remember.

DGHEIFBD GICEA BDEF BICEH EHE DEBE BCEGIAB CIHEGH

Will one be able to decode it easily? (Update, I've changed the above ciphertext two times when editing this post, all three versions are correct, I just realized both times when editing that there was a simpler and shorter way to encode parts of the message.)

I don't know how exactly one was supposed to read the actual VMS, but my bet would be on a simple method like this rather than a huge book of codes or a lengthy cipher.

The VM does not appear to be refined enough, nor important enough to to be some sort occult work.

As far as I understand, it seems to be somewhat crudely (yet skillfully) made in certain aspects, compared to some famous contemporary works.

But I'm not sure at all what you mean by "nor important enough".