I admit at first I thought it was really gimmicky, and didn't need it at all. Even when I played with the Watch in the store, it felt... foreign. But, just after about 10-15 minutes of playing with the crown, I started getting the hang of it and was making much more sense. I can't say for sure, but I think after we get through the learning curve it will be like second nature.
If this matters, I brought my girl friend to the Apple Store with me, and she doesn't use a single Apple product and is not tech savvy at all. When we went over to the watches, the thing she was most excited about was the crown. She just thought it was "cool". I think she had a bit too much customizing the watch faces using the crown.
Although that's just an isolated case, perhaps the crown is also targeted at drawing in the less tech-savvy? Would be interesting to hear how other non-Apple-geeks reacted to using the Watch.