IMO Morse code misses the point, because it doesn’t depict letters, it encodes the abstract characters into completely different “glyphs”. In particular, knowing the English letters doesn’t make you understand Morse code the way it makes you able to read Two Slice; you need to know the mapping between letters and Morse code.

You can trivially encode any alphabet into a one-dimensional graphical encoding. But you couldn’t, for example, have a remotely intelligible two-pixel Chinese font in the way Two Slice demonstrates that you can have an English one.