Lukaku is a very good player, but the reason for not getting him is rather simple: he doesn't defend. Poch and his previous players have said on many occasions that the striker is often the one who "triggers the full press," so if we have a player who doesn't even defend from the position, it's less likely they'll be adaptable to Poch's high press tactics. Bony conversely, does defend quite a bit, which to me explains our interest if it's true.
IMO though, I don't think there's any truth to us actively pursuing a striker at this point. I don't think we'll be selling Ade or Soldado this window unless someone in Spain became desperate and is talking of anteing up, but I don't think it likely.