Several years ago, while I was at UT Austin, a guy from Google (Their Translate team? Sorry, I don't remember his name.) came and gave a talk on Voynich.
The punch line of one of his stories came while he was discussing the history of attempts to interpret it. One character had a dense theory that involved, as a step in the middle, involved the text being an anagram. The problem being that anagramming destroys information and, given a large enough text, is impossible to reverse. (Interestingly, this is why some 17th-18th century scientists who were obsessed with both secrecy and precedence published their results in anagram form---if someone later came along and published the same result, they could say, "See, I was first; here's what that gibberish means.")
My point being that if you're going to posit an "out-there" theory, you have to make sure your theory can get you back here.
For a short text, you may have a point, but for a text as large as the Voynich, information content is a pretty reasonable way to examine what's going on. The number of characters (as far as I know (http://www.voynich.nu/transcr.html)) is within the range of alphabetic writing. (Alphabets have <100 characters, syllabaries typically have a few hundred (Note: English has something like 5000 syllables.), and "morpho-syllabic" languages like Chinese (Thank you, John DeFrancis!) have a few thousand.)
To have more bits per character, the document would have to have more different characters. To pack more bits in via position, for example, would be possible, but you can't go crazy with the idea because you still need to be able to decrypt it. (Hangul is a neat example; it's alphabetic, but written with the letters arranged into blocks representing syllables. Neat!)