The colours are a good idea to differentiate the fighters but I still think they haven't grasped why it is that not many people will buy them.
MMA fans and fans of team sports have a different psychology. Team sports fans grow up identifying strongly with a team and they want to show that. These shirts are more like UFC shirts than anything else. Most fans have mixed feelings about the UFC as an organisation and identify more with individual fighters.
Also, fight shorts are not ideal for every day wear. No pockets gets old fast. But how many people who actually train will wear their Conor McGregor fight shorts at the gym? What percentage of MMA fans train anyway?
Also they're expensive and look even more like power rangers now.