Creating a skybox can sound pretty easy - 6 textures that blend together at the edges without any visible seams. Simple ones, like clear skies, can be done quite quickly and without too much trouble; more elaborate ones, cloudy skies - multiple types of clouds, can be a pain if you do not have a development process to follow. I think that's what discourages people to create their own skyboxes. There aren't that many tutorials on how to create good quality ones and most of them are completely outdated; and the ones that are valid don't follow the same method.
I think that a lot of people on this forum would appreciate a clear and relevant tutorial on how to create a skybox. I know I would.