Ironically, ANH is the odd man out without the extra hull boxes. Actually, even though the ANH set Falcon didn’t have the extra hull boxes, it DID have one of the “landing legs” in the guise of the pipe-looking utility in the exact location of where the landing leg would protrude (from beneath the hull box) in the next film. Since it was a half Falcon, only the right side support “leg” was there. But it was necessary to include it even in ANH for stability/safety reasons. After it was decided to make a full set Falcon for ESB, rather than having to disguise TWO safety supports as two such “utility pipes” appearing no mater where the Falcon landed, someone finally figured out to “celebrate” these additional supports as actual landing legs. The new hull boxes were added for consistency.
All this information in first post