I think the only thing holding me back from creating my own campaigns, other than time, is that set of guidelines to ensure a quest is balanced. If that was provided then this game would be limitless in potential. I really feel I could come up with a much better story than what is provided and I'd love to mix in a few single encounters with larger maps into the campaign instead of everything being two smaller quests. I've stated earlier that I wish they'd slow down the expansions just to save my wallet but after seeing a city expansion announced, I'm giddy for more! That was a direction that I did not see coming. With all of the different heroes, monsters (I have D1), classes, overlord cards, plot decks, etc, there is so much variability that no two campaigns would ever play out the same. For me the only thing missing to truly take this game "over the top" is the ability to easily create my own balanced campaigns. If the guidelines were there this game would be perfect. I'd also love to see an official storage solution sold to hold everything.
I could not agree more whole heartily. In my experience, there are a number of ways I see balance. Such as divided attention syndrome, as I like to call it. Anytime heroes or the OL have to divide their resources to accomplish their goal while keeping the other from accomplishing theirs is sure signs that a fail is in order. A good example is "Armed to the Teeth" and "At the Forge". In the first, the heroes have their attention divided so the OL has the advantage. In the later the opposite is true.
Another is numbers. Monster numbers is one way and reinforcement numbers is another. Many times when I get two monsters a turn back in my pool, the heroes struggle allot. Most of the time, downing one monster a turn is hard. Downing two is harder. Downing three to make my numbers less is taxing.
I am no expert, so am very sure it's more complex then that, but that is what I have learned.