An Inscribed Oracle Bone and Chinese Characters
The inscriptions on the oracle bones have become very important historical evidence in the study of early Chinese civilization. The oracle bones, known in Chinese as jia gu wen, are either tortoise shells (jia) or ox shoulder blades (gu) with scripted texts (wen). The first oracle bone was discovered in 1889 in An Yang County, the capital of the Shang Dynasty (1,600-1,100 B.C.E.), and so far nearly 100,000 pieces have been unearthed.
It is believed that the original function of the oracle bone scripts was for fortune telling. The scripted bones were thrown into fire, and the priests read the crack signs from the bones and told fortunes. The inscriptions on the oracle bones represent the earliest form of the Chinese written language. Unlike most of the languages in the world, the Chinese language has never evolved from its original pictographic and ideographic structure into alphabetic or syllabic form. It maintained its ancient flavor into contemporary times, due largely to China's long period of cultural isolation. The chart shows the evolution of early Chinese writing from pictogram to ideogram and to phonogram.
Interestingly, a recent newspaper article argues that the rise of technology is threatening the prominence of traditional written Chinese in favour of their pin yin, which is a version of the way the characters are sounded written in our alphabet. The original Chinese calligraphy took many years to learn and with the advent of technology input is being placed in other areas. China is isolated no longer, it seems.
According to the text that you have cut and pasted in to this question, it is China's "long period of cultural isolation" that caused them to keep their unusual and rather difficult system of writing. What this means is that China kept to itself for a very long time and so it was not exposed to outside ideas.
For a long time, China was the dominant force in its area. Other cultures around China were influenced by it, not the other way around. That is why, for example, Japanese writing is based on Chinese writing.
Because there were no other large and influential civilizations around, China was not influenced by anyone else until the Europeans started coming in large numbers in the 1700s. By this time, the writing system was deeply ingrained into Chinese culture.
I would have to say tradition and respect kept their writing system in tact for so long as these two types of values played into the fact that with them, there would be very few challenges to the way things are done. Also, their isolation with other societies did not let any foreign words into their system.