Chinese Calligraphy History (3) Why was pictogram characters changed to non-pictogram characters?

I had not thought this question before I was asked a few years ago. There is no any answer for it, even no discussion on this question online or in books. What I think is that the Chinese Characters were first used as symbols for divination, not a language. The symbols were drawn differently by different people, e.g.

All above are shell bone script (3000+ ago) of Vehicle.

All above are shell bone script of Toot.

All above are shell bone script of Fish.

As more and more communication of write were needed, the multiple version of one character made confusions. To better communicate among people, the unification of characters was needed. So the first Emperor (259 BC - 210 BC) ordered to unified characters into Small seal script by Minister Si-Li.

The Vehicle became

The Tooth became

The Fish became

The Small seal script was the official script, any other forms were wrong, and not allowed to be used in official documents.

Small seal script is formed by smooth curves, symmetric, and beautiful, but less pictography than Big seal script or Shell bone script, which is the cost of unification of characters. Because language requires standardization, not artistry.

Chinese characters continued this trend to clerical script (Han Dynasty, about 2000 years ago to current), in which

is Vehicle

is Tooth.

is Fish.

Most curve lines disappeared, more straight lines, which is easy for everyone to write quickly. But most of pictography has been lost.

Unlike Small seal script from the Emperor and government in very short time, Clerical script was from ordinary people gradually evolved in hundreds years, accepted by government later on, so it lasts long, and still popular now. Small seal script was only limited in government documents at that time, and not popular. It is only used for seal characters, and calligraphy artworks.

Chinese characters continued to change to standard script (Tang Dynasty, 618 - 907) and song typeface (Song Dynasty, 960 - 1276),

Vehicle

Tooth

Fish

All above simplified song typeface lost most of original pictography, but the straight strokes let people write them easier and a little bit faster because the number os strokes is reduced. However, students have no idea where the characters are from, why they should be written in these forms? So they have to memorize them.

In the long history, Chinese gradually evolved from artistic symbols to standardized characters. Finally, Chinese characters completed the change from pictographic symbols  to non pictographic language characters. From the view of language, it is good because it is easy to write, it reduced the confusion. But from the view of art, it has lost most artistic pictography.

However, we could see the evolution of the characters in 3000+ years. Even song typeface has some pictography left, just not much.