The Voynich Manuscript is a cipher because...?

[-Job-]

It's hard to see a sensible motive here.  I guess you could argue that there doesn't necessarily have to be one, and that the creator of the VMS could have been foolish or insane (despite having apparently been one of the greatest cryptographers of all time).  But when you combine the fact that the properties of the text itself are incompatible with any known type of cipher with the fact that many other subtle aspects of the VMS seem incompatible with a cryptological intention, it seems more reasonable to conclude that we're not looking at a ciphertext here.  Especially since I don't see any convincing positive evidence for a ciphertext being presented.

You're mostly arguing for the general improbability of a cipher, in several cases using the logical fallacy of argument from incredulity.

Most VM theories may be depicted as improbable. For example, what's the probability that the VM contains an unreadable natural language which exhibits no clear association with any other known language?

Your premise that low entropy is only compatible with a verbose cipher is false, AFAIK. For example, null characters can also lower the character entropy depending on how they're employed.

Also, relating the VM's low character entropy with Japanese or Hawaiian without accounting for its other properties is comparable to classifying the VM as a verbose cipher without accounting for the word lengths.

Is there a language or cipher that matches all of Voynichese's features? I think that should be the focus of this discussion.