Nobility and honesty accompany increased friction with the world [and thus more turbulence and suffering], and noble people (like Arjuna), instead of considering passivity and avoidance as the only pragmatic solution, and the ensuing troublefree-but-pale life as the only feasible way to exist, should recognize that there are greater possibilities of powerful tranquility. That is why one should read the Gita.
Sensitivity accompanies more instability, and sensitive people, instead of considering falling back to complacency, coziness and insensitivity as the only practicable solution, and the ensuing inert-stability as the only feasible way to exist, should recognize that there are higher possibilities of regal and dynamic stability. That is why one should read the Gita.
Man will one day realize that even a little probe into the affairs of the world leads to endless and vicious intellectual arguments that are incapable of authoritatively deciding what is right and what is wrong, what is good and what is bad; and realizing thus the bottomlessness of the rabbit hole, and the impotency of his conceited intellect to resolve the puzzle of the duality, man will inescapably yearn for transcendence. That is when one should read the Gita.
And then, he should know that this tranquility, this stability, this transcendence, which he is intrinsically yearning for, is to be, and can be, accomplished right here, and not after his death in some unknown heaven. That is why one should read the Gita.
After investigating a great deal about things which exist around him, including his body and mind, man eventually reaches a point of saturation, and drawn by inevitability, shines his glorious power of enquiry at his own existence. He should then know that therein is the transcendence that he is seeking, and not somewhere up in the sky. That is why one should read the Gita.
And if he has NOT reached the aforementioned state of nobility, sensitivity and saturation yet, Gita will not be of much meaning to him. He will only end up misunderstanding the text, and get caught up in the juvenile philosophical arguments of monism and dualism, and in the fanatic debates about the supremacy of Krishna and Shiva (or whoever else). Instead of raising himself to the level of the text, he will only drag the text down to his level, and use it to merely satisfy his trivial urge to quarrel. :-)
Gita is not just a book of morals and ethics; its purpose is not merely to preach us about good and bad. Its message is transcendence. And that’s why it stands apart from other preliminary ‘scriptures’.