Nina Silber argues in The Romance of Reunion that white Southern men came to represent virtues that some Northerners feared were disappearing from their culture. Specifically, they were worried that racial, class, and gender hierarchies were breaking down because of capitalism, immigration, the women's movement, etc., and the South represented a world where these hierarchies were still intact, where men of quality could be swashbuckling heroes and women could wear petticoats (she talks about how Southern women were supposed to be more beautiful than Northern ones -- the Northern ones looked "consumptive" basically because they were too liberated and tried to talk with men about politics and culture, but the Southern ones were giggly and pure). I don't think she writes about these movies specifically, but she does a good job of explaining the ideological underpinnings of Northern sympathy for the (white, formerly secessionist) South, and why the Confederate soldier became a pop-culture hero around the turn of the 20th century.

Err, why does this have the shopping tag?

The films you mention were all released during or within months following the end of the Wilson Administration. They were also quite popular outside the Northeast.

You might consider these films to be part of the institutional backlash against Reconstruction that began with the Civil Rights Cases of 1883 and continued through Plessy v. Ferguson (1896), the Spanish-American War and finally the Wilson Administration. The overall aim seems to have been to reintegrate the Old South back into official Washington.

After about 1877, "waving the bloody shirt" to scare up votes from the GAR and old abolitionists became a matter of public ridicule.

Birth of Nation is an example of the South waving its own bloody shirt; a narrative that continued to be very strong until the 1970s.