Regarding chopsticks and one-handed eating: you could do the same with a fork, as long as the food is already cut in small bites, like Asian food usually is.
On the other hand you cannot eat a steak with one hand, neither with chopsticks nor with a fork.
I think that the good design is in the food, rather than in the chopsticks.
Forks don't work as well with certain kinds of foods. E.g., you can eat snacks like chips or cheetos with chopsticks without getting your fingers messy which is more difficult to do with a fork. Same with slippery food like certain kinds of noodles, and hard foods like some nuts.
There's just a certain simplicity and universality to chopsticks that appeals from a design sense... That said recently I've been into using a Spork which works great for some foods and is another interesting study in design...
I can eat a schnitzel with a spoon. :) I can eat almost anything with a spoon. I can't eat slippery food with chopsticks. With fork I just turn the fork like a screwdriver.
On the other hand you cannot eat a steak with one hand, neither with chopsticks nor with a fork.
I think that the good design is in the food, rather than in the chopsticks.