Some people could not possibly order any faster, and got delayed by weeks. The store app did not come up at the same time for everyone. Other people have disabilities and are unable to click through very fast. Some people wanted to use a gift card and had to wait 10+ minutes for apple.com. And some watches started off at 4-6 weeks and have yet to be delivered.
All of those are Apple's fault due to significant supply constraints. Sure they told you the shipping window, so we are aware. But imagine the shipping window was 2016-2017. Or imagine you have severe arthritis or vision problems, you were a little slow so your watch was delayed for 2 months. Would you still feel the same way?
Everybody would feel bad, but what should Apple do? If Apple could deliver faster, I'm absolutely sure they would, but if somebody in the supply chain has problems (haptic engine), there is nothing, that Apple could do, but ship as many they can, as fast they can.
First Come, first serve. I had my order for a 42mm SpaceGrey on 0:01, and for 38mm Sports White on 0:02. I got both my watches on 24th, it wasn't close to be impossible!!