The avatar world is becoming more modern. there are now phones, cars, clothing is different, radios, and now there are airplanes!! do you like that? before we got the authentic look of western culture. Now we a mix of western culture and the victorian age. I personally think the avatar world became a little too modern to fast.
In the last episodes I noticed that the weapons were modern. If you look on the United Forces ships are... well modern. Even the equilist they just added bombs to the equation.
The thing is don't you think it is a little odd seeing cars being driven down the road instead of animal drawn? whats next computers? Cell Phones? Texting? TV??