Then again, some of the difference in attitudes and approaches here may derive from historical fields. Maybe historians in Lord's field are especially resistant to using physical artifacts. To a medievalist, however, physical objects are at once rare and necessary. They're rare, and far fewer survive than from the nineteenth century U.S., so the opportunities to use them are more limited. Thus, they may not offer quite the same revelatory possibilities as physical objects from other eras - not in kind, but in degree. Conversely, however, medievalists have so few sources, relatively speaking, that we tend to use any and all we can find, including physical artifacts.
I would add to her comments that medieval historians tend to have a closer relationship with their colleagues in language and literature departments than other historians do. Medieval historians will have to consult with their counterparts on issues of language, for example, much more often than a scholar of American history will. This is not to say there is no crossbreeding in other periods, but instead to point out how much more common it is for medievalists.
I suspect that's why medieval historians have such a respect for the material text (i.e. manuscripts, etc.). In the comments section of New Kid's post, Bardiac writes, "Material culture is one of those places lit folks like to invade :) Everything's a text!!" For medievalists, the text IS material culture. Outside of medievalists, no one else in an English department is allowed to do paleography -- indeed, non-medieval literary scholars rarely understand more than the most basic ideas of scholarship of the material text, which probably explains why Jerome McGann's work is considered so cutting-edge among Early Modern literary scholars, while medievalists tended to respond "Well, duh. Everyone knows that."