My perspective is that the Abhidhamma Pitaka constitutes a Dhamma Theory that attempts to systemise the teachings of the Buddha (as recorded in the Sutta Pitaka) in such a way that they capture the technical essence of the teachings without reference to conventional concepts or references to self. Quite possibly it was a reaction to heretical monks and rival early schools who insisted on the existence of some kind of atta, puggala etc. In turn, the Abhidhamma would be classified as Buddha Word because it was well spoken.
Origins aside, I think it's a very valuable and complementary tool for understanding the doctrines of anatta and anicca. My concerns about it are when it extends beyond the scope of the suttas, presumably to fill certain gaps in a well-rounded and comprehensive Dhamma Theory that couldn't be satisfactorily answered by the suttas alone. Using the Simsapa Sutta as a guide, I believe that things that the Buddha didn't teach can be safely left to one side, so whilst I find the Abhidhamma interesting and insightful, it doesn't play a central role in my practice or understanding of the Dhamma.
“I hope, Anuruddha, that you are all living in concord, with mutual appreciation, without disputing, blending like milk and water, viewing each other with kindly eyes.” (MN 31)
What is the final conviction that comes when radical attention is razor-edge sharp? That the object of the mind is mind-made (manomaya). (Ven. Ñāṇananda)
"If you have always believed that everyone should play by the same rules and be judged by the same standards, that would have gotten you labeled a radical 50 years ago, a liberal 25 years ago and a racist today." (Thomas Sowell)