As long as it doesn't kill balance vs f2p players, I think it's ok. I can see the upside of spending money rather than time, which is the only option for some.
I can easily see Blizzard get greedy if it takes off though, aggressively pushing new items for players to keep the edge, like fucking seasonal arena gear for real currency.
Skill should obviously be more important than wallet. But skill often gets dominated by people who have shitloads of time. If I could spend a few dollars and play fewer hours, that makes sense to me. At the same time, many things should only be available through actual gameplay.
PS i heard this game only has consensual pvp, does balance even matter in this game?