I wanted the gunslingers to feel different from other characters in Into the Odd games, since gunslingers in We Deal in Lead can travel into other settings and systems.
Having gunslingers hit 100% of the time removes a lot of the drama, though I know a lot of people see adding a to-hit roll back to ItO-based systems as sacrilege.
Having the chance of a miss or misfire adds stakes to gunslinging and offsets the fact that artefact guns bypass armour and can hit magical creatures.
Even Roland in the Dark Tower misses, often at the worst times.