I actually think masterwork weapons have become more useful than most exotics due to the orb generation (especially in activities like the Nightfall and Raid). Having a rocket launcher with the ability to generate an orb of light on each multikill is more useful than the Wardcliff Coil whose rockets will randomly track different targets and give me no bonus on a multi kill. Same goes for just about every exotic and with how weak the Destiny 2 exotics are compared to the ones from Destiny 1, there is no real reason to use one of them unless you do not have a masterworked version of a legendary weapon that fills a similar role.
Bumping this post. I want to use Jade Rabbit as my kinetic primary, but might as well make Nameless Midnight a masterwork for the orbs because it will then be superior. Why can't exotics be masterworks too?