My Answer: First of all, since The Zohar is written in Aramaic, the ancient language of Babylon, modern readers cannot understand it. Furthermore, The Zohar is written in a style filled with allegories and images that appear corporeal to us. We would not be able to detach from these corporeal images when reading The Zohar without the Kabbalistic Sulam Commentary on The Zohar. This is why, by combining the original Zohar text with his Sulam Commentary, Baal HaSulam introduces us to the correct understanding of The Zohar and the proper structure. Through this we can begin to see the entire text through the three lines.
The three line approach is necessary. Even the Torah is approachable only through the three lines. It is written entirely by way of the three lines: We need to take the two lines given to us from Above, the right and the left lines, the desire and the Light, and connect them properly. We build our soul by properly combining these two lines.
It is impossible to study The Zohar without the Sulam Commentary. This method, called the Sulam (The Ladder) became revealed and added to The Zohar when our generation came to the point of being ready to study the wisdom of Kabbalah. This is the time of correction. As the global crisis becomes revealed amongst the souls, we can now use this method to its full extent.
In addition to including the Sulam Commentary, we slightly modified the text of The Zohar by abbreviating some technical details to make it more accessible to the modern reader. This is why we have named it Zohar for All.