The clothes are not just cosmetic, most of them bundles along with perks to help boost your XP. There are more than 12 clothes store which sell different clothes with perks, and it takes me around 1 hour to visit every single outlet to buy clothes as i achieved certain level.
What i found pesky is the clothes stores that all scattered around the city, it does not allow you to compare the stats and style of the clothes that you owned. +The martial arts will amaze you because the high level of authenticity and fluid combat system, the vehicle controls were great, unlike GTA and watchdogs, very shaky, saints row was too easy and unrealistic.