vi is an acronym for "visual interface"

Developed by Bill Joy in (approx) 1978 as a replacement for ed/ex

ed was an old command-line-based editor designed for Teletypes.

vi was designed to be usable over 300 baud modems   (i.e. minimal data transfer)

vi "does one thing and does it well"   (i.e. obeys the Unix tools philosophy)

vi is a text editor.