While AAA means one thing to a set of people, it means another to another set. It may have AAA budget/scale of production, but Mirror's Edge isn't a great sales driver. Pre-order numbers aren't good. Late nights events are not given hours for. So on. Doesn't matter when it launches. I don't see EA touting pre-order numbers for the game. It's the most niche "AAA" game out there (and I'll be happy to play it when I can).
I don't play shooters or MOBAs. May is pretty weak to me. Why are people excited? Anyone can do this.
It's certainly killer to a group of gamers who love niche and RPGs games. A ton of great games in June. Including this one now. Although, Beta impressions are all over the place right now.