Harvard physicist's take on the VMS

[Jorge_Stolfi]

Or should the letters reflect the exact position of the tongue and the corresponding airflow?  

Hangul, the Korean script, was supposedly based on that idea.

But even without going that far, one could at least use similar shapes for corresponding voiced and unvoiced consonants (P-B, F-V, T-D, K-G, S-Z, Sh-Zh, Tsh-Dj), with a systematic detail (like an extra stroke in a specific position, or a left-right reversal) to indicate the voicing. 

And make lower case be just a smaller version of upper case. (Cyrillic does that for most letters, but then it has "m" as lower case "T"...). 

And use only short (x-height) letters for vowels, even in upper case, to leave space for diacritics (if and when needed).

All the best, --stolfi