Colour 4x5 film is more common and cheaper. Not to mention enlargers. Or you may want to stick a roll film holder on the camera.
Most of the reasons to use a smaller camera apply to reducing backs. I've got 5x7 and 4x10 backs. Plus a 6x17 roll film back. I could crop all three out of a sheet of 8x10 but it doesn't take much film to cover the cost of the reducing back and holders.
Yes - well I see your point about 4x5 film being cheaper - I wasn't suggesting cropping 4x5 frames out of an 8x10 sheet - I was suggesting using a lens with 8x10 film that gives you the same FOV as the lens you would use with 4x5 film.