Variety is favored in many areas, particularly for activities which extend over time. Humanity balks at the prospect of the straight road, the assembly line, the prison cell—we are designed to respond to stimuli which vary; inertia generates invisibility. Perhaps this is why the old style types, with their lively complexity of form, are still preferred for extended reading.
The idea that a character should always be represented by a single glyph (except for the occasional ligature) is an economy of the foundry type era, with no benefit to readability. It also expresses the reductive ideology of modernism, and that too is a thing of the past. New technology makes possible new practicalities. The Neology fonts automatically mix Deco (geometric) and Grotesque letter forms in a pseudo-random manner.