In my opinion they shouldn't exist, why would you use a Bad JuJu or multi tool or whatever if you can use a primary that takes down some shields 10x faster in addition to the fact there is always some sort of element burn, I just don't think primary exotics are any good in PVE except for the Vex, so I think that the only elemental weapons should be exotics because that would make them even more unique and desirable