That's precisely why they designed it this way.
What? Can you explain what you mean here or is this just Apple hate?
I find it hard to believe that any company, much less one with such a high reputation for aesthetic, would design something specifically to irk people.
I think it was designed rectangular because it’s easier for smartphone app developers to make watch versions of their apps, easier to display data, and generally fits with the look of the rest of their rounded rectangular products.
As a watch it isn’t as visually appealing, but as a device it’s (arguably) more useful.