I don't think there is any hidden meaning to hanging pictures in stairways and hallways. Both often offer large expanses of bare wall,and people like to look at family portraits or art work in their homes. I've seen very attractive "stair step", staggered groupings of framed family portraits that sometimes mimic the elevation of the stairs, on walls adjacent to stairways. I've seen quotations, scripture, inspirational words, etc. in the form of vinyl lettering, placed among the pictures.
In my own hallway, I have one long (4 and 1/2 ft.) framed print at the end of hallway going into the living room. it is visible from the living space. In the hallway near my bedroom, I have a smaller framed print of a young woman, with a rustic metal key hanging above it. Both pieces of art work fill otherwise blank spaces, add texture and color to the walls, and give me pleasure when I look at them while walking down the hall, which I do dozens of times a day.
Hallways and Stairways are good places to hang unusual pieces or art that you love but that doesn't "match" or go with furnishings in other rooms.