Why is Ultra so ugly? Because the day Apple makes an Apple Watch with even a slightest hint of new design and better design the whole Apple Watch lineup is going to look outdated.
Many would not be interested in wearing an outdated piece of jewellery. And many will not be interested in buying a watch which will go become outdated in few years.
The whole Apple Watch product will be doomed.
That's why all the Apple Watches looked the same. Contrast it with the iPhones which Apple actively tries to look outdated each year with at-least one identifiable design change.