sorry but dancer is not mandatory for "high end" raiding in a way most people think of actual high end raiders, i.e. the "we go for world first" way. its mandatory for speedruns and even than only because speedrunners literally don't give a flying **** for the 20 runs were dancer performs worse than mch as long as at the end they get their one run where dancer suddenly has every procc in existance on his side. for one its a sad joke at best to try to balance around that kind of play, especially as square does not support it in the slightest, given their stance on the very tools players use to upload and parse these fights. Also, given the current level of dps even if bard was dancer 2.0 you would not want both of them. even in these very specific (i.e speedrun) settings, at the end of the day dancer is still only the best physical ranged for speedkills, the role as a whole is still bad enough you would hardly want two of those.
the extreme synergy between Bard/Dragoon was flat out broken, especially do to crit scaling