* No baseline or other orienting structure, so vertical shifts easily change meaning ("ab" turns to "bc"), same for rotations.
* No redundancy to allow for recognizing incomplete / garbled / damaged letters.
Both features are prominent in any machine-readable encoding (like bar codes or QR codes), and are relatively easy to find in any human script.
The idea behind making more compact visual representation of letters has merit. This particular implementation of it is impractical, though. It only looks acceptable on a demo page.
(While at it, I know two well-designed phonetic writing systems: Tengwar and Hangul. Neither is super compact, but both are easy to learn and read, because of the internal logic. Dotsies are way more arbitrary; they don't exploit any connections between letter or sounds they represent.)