because some exotics suck, and others are great. for instance, im gonna enjoy ntte for general pve use if it had a elemental fix id have to farm forever trying to get one of each element you have no control over the element you want i dont want to have ot use a handcannon just cuz its the only fire element primary. its basically a HUGE RNG grind at taht point, or you use subpar weapons soley due to burn. id like to not feel punished for messing around with different weapons.