Liverpool play in all red. Season in, season out. Not sure they "have trouble marketing" their kits. They sell shedloads. More than we will be doing chequerboard one season, Ajax another, plain red the next, sash, reverse sash, hummel retro, plain red again.
Fans, or if you like, the general public don't really want perpetual change in something as inane as a football shirt. As a kit anorak you might but the rest of humanity doesn't.