A physics textbook always becomes larger on revision. Actually, these are references that strive to include everything, and are not meant to be taught serially, but used as a resource. In physics, this can be done successfully and reasonably, making students sharper, not duller. The real virtue is in a concise textbook that introduces and teaches thinking skills. History is actually full of drama and emotion, not dry at all, but this would never be gathered from high-school history.
History is also argument and controversy, and strengthens the mind.
High-school history is, in fact, not history but something much less and nearly worthless. It is only a Disney history, with warped and altered facts and interpretation. One contemplates with unease the possibility of standardized tests of minimum competency in American history, to accompany those in reading, writing and ciphering. The output of the basic skills of reading, writing and ciphering is easy to see and evaluate. That of a basic skill in history is not so easy to characterize.