There are various italic designs from those in which regular is inclined almost mechanically to those that are much more organic than regular with movement. Depending on the application and assumed usage, the design difference of regular and italic differs in scope.
As typesetting in long sentences is assumed for the regular font for text, ease of reading is prioritized over designability in many cases. However, typesetting for italic is often done in a few characters to few lines, so the freedom of design is relatively high.
Therefore, italic can be in the iconic position within the family to highlight the font personality.