When I saw the images I thought they probably weren't meant to be offensive at the time. At the time, similar images were seen in National Geographic, neighborhoods filled with new immigrants, photos from people who had travelled in cultures that had not been as globalized/Westernized as they have been today.
Mr. Geisel and his publishers, likely all educated white people, probably saw the world through this lens. Do these images reduce people to "other" characteristics? Yes, they do. At best, these images seem dated and condescending by people who assumed their culture was the best, the ideal, that others were striving to achieve.
Had someone Black, Asian or otherwise pointed out at the time that these images somehow stereotyping or objectifying, one can imagine the puzzled look on the faces of Geisel and his league. "But that's what they look like, isn't it?"