It is better enough in an arena setting to start mattering for the top 10% of PvP players, I am not one of them but it is easy to see the complaint of people who have been largely forced to play horde for PvP suddenly needing to switch to alliance to remain as competitive as they were in their bracket. It’s niche, and you can whatabout-vanilla-classic this all you want, but their argument is correct: for certain roles in PvP humans will be the best class and for the people competing in higher brackets they will have to faction-swap.
Does blizzard care about this niche issue? Probably no, and they also have incentives to ignore it for extra income, but it is bad design that frustrates their customers and the frustration is completely understandable if you are one of those players.