You are most certainly right that I don't main Bard. Maybe that affects my opinion but then again, probably not. It is my third 60 and my DPS class of choice, was pre-HW and so far still is and I played it in SCoB and extremes on frequent occasion so it wasn't like most of the other classes that I got to 50 and let gather dust. I do have a connection to the class and have enjoyed it very much as my DPS class.
But again, my point isn't on how it matches up to other DPS. I don't have the ability to parse so I have no hard evidence as to how their damage is compared to others. I am not arguing they are on par, because it definitely doesn't seem like they are, or at least, not close enough to justify the "support" tradeoff. I was simply taking the stance of WM being a tool for bards to use as a self-buff, that actually does buff you. That's what I have seen so far in HW while both playing and not playing the class.
It definitely changed the class and its unfamiliarity is, in my opinion, the biggest cause for concern for old Bards. Whether inability or desire to learn or simply just not fitting their playstyle, its not surprising for the cause for concern. People who like the class will stick to it and people who don't like the change in playstyle won't.
It shouldn't be a surprise that the old playstyle has scaled poorly. The old style excludes 3 of the 4 new (not counting WP) abilities, which are supposed to be a part of that scaling. For better or for worse, the abilities are part of the kit and utilizing them is a necessity.
Since comparison seems to keep coming up, it still seems like BRD/mch both need some potency increases to scale them back into a consistent 90%ish range of other DPS classes. Then again, old bards have the most adaptation to do in HW and I think the majority haven't figured out how to completely adapt yet, which would be a huge factor why they on average seem further behind.
As far as the playstyle, I think it is a good thing. The old playstyle was a complete joke. No rotation, keep things off ogcd, run around and ignore mechanics constantly made bard the hands down easiest class to play. It was at the point where Bard was the new derpgoon and the only differentiation between a good and bad bard was if they knew when to play songs on their own. WM alone adds a whole new range of decision making and paying attention that will make it more challenging and mostly more rewarding and this brings them in par with other classes, in that regard.
You are right, all that there is for bards to do is to get better. Whether or not it was the right way to make the class more challenging, the deed is done and this is bard now.