Now pretend that you've been playing Bard for an extended period of time, not just a couple of weeks.
Pretend you've adapted to a playstyle that demands you be able to double oGCD without pushing out your GCD, that you queue your GCD weaponskills so they fire off ASAP, that you catch your Straighter Shot procs as soon as they happen, before the skill icon is even highlighted. That you accept your lower DPS ceiling as a result of trade off for mobility and utility, and don't mind it because you enjoy the way the class plays and pulling off the silly number of button presses in the opener without missing anything.
Now you unlock Wanderer's Minuet. You can't double oGCD without pushing out your GCD. One of your strongest attacks--Barrage into Empyreal Arrow--demands you intentionally push out your GCD. Queuing weaponskills means your oGCD instants now interrupt them. Catching a Straighter Shot proc immediately no longer even works. Mobility is gone, traded for as little movement as possible.
In return, you get... Nothing. You're still capped lower than "real" DPS--it's baked into your weapons and not going anywhere. There's no strategizing behind it. There's no new flow or groove to fall into, the playstyle of Minuet is by its nature stilted. The class feels less cohesive and like a different animal, for absolutely no gain to you.
The issue isn't that Bards can't handle Minuet. It's that it's a badly designed system, not terribly fun, fairly unrewarding, and counter to the basic strengths of the class pre-Heavensward. You could play stationary turret-bard in 2.x and it was still better than Minuet because the skills worked together. I've done everything but Alexander on Minuet Bard; I just legitimately did not enjoy it. It's not about difficulty, it's about fun, and that is why MCH is currently kicking Bard's ass.