The question isn't how much randomness there is in the game, but how the player can manage it. In other words, ultimately, how much control the player has over the situation.
The problem with games like Heroes from a competitive point of view isn't the randomness, but the fact that a single game takes too long, especially in the later parts, unlike parts 2 and 3. However, we've strayed quite far from the main topic; I was just very surprised by the phrase "non-turn-based battles." :)