From the many responses, it seems that one of the main reasons is “it’s fun”, and it’s part of trying to have an “authentic” eating experience.
The way I see it is as if you went to a country where everyone dressed in Chinese clothes whenever they went to a Chinese restaurant, or whenever they ate Chinese at home.
If you grow up and do this all your life, and everyone else does so also, then yes, I guess it would feel strange to show up at a Chinese restaurant wearing western clothes or eating Chinese at home wearing western clothes.
I would understand the attitude, but, clearly, someone that is a foreigner to the above country would find it a bit strange to change clothes just to eat food from a particular country.
That’s somewhat how I see the use of chopsticks by westerners when they eat Asian food. It’s part of the experience, they’ve always done it, and everyone else does it, and it feels weird not to do it, but when you get to the bottom of it, the utensil you use need not reflect the culture the food came from, just as the clothes you are wearing don’t need to, either.
First, I always use a fork, and I am just as dexterous at picking up any Chinese food as any Asian or non-Asian chopstick user, so it’s hard to see the use of chopsticks by westerners being based on an advantage in ease of eating Chinese food.
Second, from what my Chinese former roommate and some Chinese friends tell me, Chinese people do not use chopsticks to pick up rice from the plate and carry it to their mouths, like westerners who use chopsticks do. They put the bowl of rice up to their mouths and use the chopsticks as a shovel to scoop the rice into their mouths. So, it’s not like chopsticks are “ideally designed” for Chinese food, since you can use any utensil to just shove rice from your bowl to your mouth.
In fact, a Chinese friend today mentioned that, when he eats with other Chinese people, where it is considered OK to shove rice into your mouth, he uses chopsticks, but when he eats in the company of westerners, where shoving rice into your mouth is not considered very polite table manners, he uses a fork, because, for him, it is easier to carry rice from the plate to the mouth using a fork, than using chopsticks. So, again, I’m skeptical of the use of chopsticks “because they are ideally suited to Chinese food”.