One thing that I don't know whether it'd go down well with many other players but would definitely help in their "feel" would be to make songs double GCDs.

To compensate, either apply plenty potency buff to other GCD actions or - IMO - make the unique effects of each song stronger.

But add an ~5s window in which we actually play, with a proper song that you can actually hear. Bonus points if it's a moving-cast where we're slow (but then further buff songs or other actions to compensate for time lost due to not being able to use it at a specific moment).