From Monospace to Duospace: In Search of the perfect writing font:

Designers have pointed out that, with all the structural benefits that may or may not come from using a monospace font when writing, there are typographical compromises in typewriter fonts that are mere mechanical constraints that can and should be overcome. Due to the way mechanical typewriters worked, using the same horizontal space for each letter was inevitable at the time. As beneficial as this regular rhythm is for writing, do we really need to squeeze every letter into the same square? Can we not at least make some exceptions?