My theory is that people generally enjoy the Epilogues because the Epilogues have the official Homestuck branding. The same way people watch Robocop 3 because it has Robocop in the title and stars Robocop. If the project did not have Hussie's name attached to it, and was posted exclusively on AO3, it would probably be ignored as a marginal piece of diaper fetish literature, indistinct among a sea of its own kind.