In 1945 Rolex came out with the first wristwatch featuring a date display with a Cyclops lens that magnify the numbers. This watch is the self-winding Oyster Perpetual Datejust.
The Datejust watch is 36 mm width while the Datejust II, released during Baselworld 2009, is 41 mm width both elegant, self winding, with fluted bezels, Oyster bracelets and waterproof to 100 meters or 330 feet. This increment of the size is due to what the market is asking for. Nowadays, women are using bigger watches so men’s watches need to be larger in consequence of that.
Now you can see the 36mm Datejust watches being considered to be unisex, although for many men it is still the right size. Now, women have more options including different case sizes, dials and bracelet sizes.
In conclusion we can say, that a few millimiters do make a big difference in design.