Do you find playing melee more difficult?

[Mhaeric]

In my experience, though, BRD/MCH is basically playing the game on easy mode since you’re fully mobile without consequence.

Bard yes, but they make up for that a bit by having a crap ton of buttons to press.

Machinist, however, is not easy mode by any stretch of the imagination. They also don't have full mobility like a Bard, because a key part of their rotation is a short range near-melee ability they have to sustain for 2 ticks. And if they mess up their cooldown rotation it has a huge impact on their dps, unlike with Bard whose cooldowns have buffer time built into them and line up well so that they're always available slightly before you actually need them even if you screw up a bit.