My Answer: No book was written from such a high level by ten Kabbalists, who represent sources of ten Sefirot. They all achieved the full correction of egoism, passed all 125 degrees, and were united as one in Malchut of Infinity. They annulled themselves so fully on all the degrees, starting with the lowest degree to the highest, that they were able to transmit a pillar of Light to us from Infinity. Now this Light is in front of every person, and every person can receive it through The Book of Zohar.
No Kabbalist or group of Kabbalists in the history of Kabbalah, starting with Adam and on to our times, throughout 5770 years, had an opportunity to do anything like this. The authors of The Book of Zohar, the ten Kabbalists, representing the ten primordial Sefirot, performed a correction from this world to the highest world. Therefore, they are able to give us the force that can correct everything.
This is why The Book of Zohar is being revealed particularly during our times, when egoism and crises are being revealed in our whole civilization. This is also the reason that it was prohibited to reveal and study The Book of Zohar in previous generations.