I think some are expecting a game that Overwatch just won't be without a complete 2.0 do-over considering the current setup of 4 players made to set up the other 2. I'd prefer more characters be tuned like McCree than the likes of Genji or Tracer. McCree is just raw ability, but the other two have way too much leeway and derpy forgiveness in their kits, but he's a bit of an oddity and their MO is more slanted towards easily digestible, generosity in hit detection, and they've made more of an instanced MMO PVP scenario than a real class-based FPS.
But I do think they bungled their underestimation of DPS popularity. It's an FPS, so people naturally buy and play these to shoot people, but there's a constant problem of too many people wanting to do that in any given match despite the equal importance the other roles take up in slots.
Anyways, I just kind of wish there was more mechanical nuance to things so that character mechanics aren't immediately figured out and basic. Things like grapple slingshotting and slidehopping in Titanfall 2 aren't hard to learn, but they're outside of the basic uses for those abilities in that game, and once you start uncovering them they add whole new layers to the experience. Same with rocketjumping in Team Fortress 2. There really isn't an equivalence to that in Overwatch -- superjumping as Genji was sort of like that but more clearly exploit-y.