For too long the topic of American History has been covered mostly by naming and knowing about the various wars that were fought and won. But there is a lot more to know, such as how people lived and how various segments of the population coped with their own hardships and by dividing it up we could learn more.
Yes, I think that the American history curriculum should be split out into more and different classes, because American history is relevant everywhere. If a child has to write an English paper and they want to write about an American history topic, they should have the option. History is cross-referenced in many disciplines.
I really don't think it is really necessary to fragment American history into more and different classes. The fact of the matter is that no matter how you present it, no matter how specifically you try, classes will always be just highlight reels of the past. There are plenty of books that do not require study space.
I believe American history could be split onto more and different classes, but it really depends on what grade level, as to rather or not it should be done. The pressures in public school simply won't allow this, in my opinion. At the college level is should be doable and it should be done.