I finally started leveling bard and between dungeons I found myself plucking around on the harp in the overworld. That made me think - why can't we use performance mode in instanced areas like dungeons and raids?

Sure, it wouldn't be difficult to conjure up a scenario in which it could be used as an "exploit" or be "abusive" in some form or another (there's a vote kick option for a reason!) but it's not like it would be a particularly game-changing addition, moreso a fun novelty. Imagine a pre-pull ditty or triumphant fanfare if you're privileged enough to have a bard in your party comp.