Just FYI, since you've used the terms twice already, bottom-up and top-down history are terms
already commonly used in historiography, with bottom-up history being a equivalent for social history or
people's history.
Historians
do look at interactions between individuals, though; they study them to understand the social climate of the time, analyze cultural movements, see the general thoughts and opinions of the populace, etc. But unless there's an actual connection to be made, they can't make statements about how these beliefs shaped the success of the overall societies. And because such evidence is always open to interpretation, you end up with people drawing conclusions to support their own needs, such as Max Weber using the Protestant work ethic as a more subtle way to paint Catholics as lazy. (Though sociologists did eventually find that his idea did have basis in fact, they've also found that his hypothesis that it led to capitalism to be incredibly wrong.)
Not sure why you're bringing up pschohistory here... if anything, that's the top-down approach, treating people in society like molecules in the Kinetic Theory of Gases (stealing that analogy directly from Asimov himself). And in any case, it's arguable that psychohistory is among the more unrealistic things in
Foundation; even Hari Seldon probably didn't expect it to work, given how he ended up creating a Second Foundation of psychics.