Bard is really weird. It's the only job I can think of where the weapon it uses clashes with the Job's theme. It's more of an Archer than it is a Bard right now, too.
To be honest they should've made Bard a caster job that has a Lyre as a weapon, and then Archer to Ranger or what it actually is right now, a Magic Archer, when they added Jobs to the game.

Machinist still makes sense because it's their staple weapon throughout the franchise. Guns are also tools, which the job has various amounts of. It's the matter of how often people prefer using that particular tool or not.
Personally I think it's better thematically now than before, because using various tools is the job theme.