I recommend the book 《简化字源》by 李乐毅, ISBN 7-80052-494-9.
For example, the simplification history of 愛 to 爱.
It's frustrating and even disgusting that the topic on simplified and traditional characters has now always been a quarrel due to political correctness, ideology, bias or even just ignorance, or what I may call 'pretend to be blind'.
The image quality is poor and it's in Chinese, so I try to give a brief interpretation of this page.
爱 originates from 行书. There are countless variants similar to the
present 爱 in the ancient writings, printings and carvings. Here are
the famous ones.
1st by Wang Xizhi, 王羲之, AD303-361 or AD321-379, Jin Dynasty.
2nd by Monk Zhiyong, 智永, dates of birth and death unknown, Sui
3rd by Li Shimin, 李世民, AD598-649, Tang Dynasty.
4th by Su Shi, 苏轼, AD1137-1101, Northern Song Dynasty.
5th by Wen Zhengming, 文征明, AD1470-1559, Ming Dynasty.
6th in 崔勤造像碑, Northern Wei Dynasty, AD368-534.
The form 爱 was widely used by the folk and could be seen in many folk
7th in Yuan Dynasty's 京本通俗小说.
8th is the same with today's simplified 爱. It could be seen in Song's
古烈女传, Yuan's 古今杂居三十种, 全相三国志平话, 朝野新声太平乐府, Ming's 娇红记, 薛仁贵跨海征东白袍记,
岳飞破虏东窗记, Qing's 目莲记弹词, 金瓶梅奇书, 岭南逸史. This one is also seen in one of
Ming's official documents, 兵科抄出. And it was also included into
手头字第一期字汇 sponsored and published by 200 public figures and 15 social
organizations in 1935.
9th 标准行书范本 Taiwan 1979.
Both traditional and simplified characters are precious legacy. It was not CCP but the Chinese ancestors that invented and used these variants. In 1935, KMT government launched to make a standard of simplified characters but this project was then cancelled. After 1949, CCP took over this project and finally made it. In 1952, Chiang Kai-shek proposed it again in Taiwan but was opposed and came to nothing. Today Japan uses Chinese characters, kanji, some of which have also been simplified.