I play Survival, so Rapid Fire doesn’t affect me at all. 
My issue isn’t about one specific ability, its about racial balance as a whole. When any race, Horde or Alliance, dominates PvP representation to the point that it crowds out other options, it’s a problem. I felt the same way when Orc’s Hardiness was a near-mandatory pick for healers in rated PvP back in BfA/SL
Even with the recent buffs to other racials, Shadowmeld still sits at 30% representation in rated PvP. If Blood Elf’s Arcane Torrent got a rework, so should Shadowmeld tbh.