[kijin]

"Organic" change is little more than the result of repeated oversight. It is often triggered by changes in hardware availability.

Scripts that were developed in the age of stone tablets will change when the tablet and chisel are replaced with paper and brush, and again when the brush is replaced with a fountain pen, and again when the whole setup is replaced with a computer. People will naturally adopt the style that allows them to convey meaning the most conveniently in a given medium.

Chinese, Japanese, and Korean were all written vertically from right to left (|||) until only a few decades ago. Now they are very often written horizontally from left to right (≡). A lot of factors have contributed to the change, such as the ease of embedding Western, mathematical and scientific symbols in a CJK sentence, the need to keep one's hands clean when writing with a modern pen, and of course the introduction of computerized typesetting.

Nobody forced anyone to write horizontally. People just gravitated towards what they found more convenient given the availability of new writing tools. And of course, many artists and calligraphers continue to write vertically when it suits their intentions better. Even better, new calligraphical techniques have been developed to take advantage of unique opportunities that horizontal writing offers. As long as everyone gets what they need (art for artists and utility for utilitarians), I don't see any problem with this arrangement.