The fourth installment was an experiment. And as an experiment, it provided very important information. Everything you listed doesn't need to be done. Because, if it weren't for the experiment with the fourth game, the world would still be demanding armies without a hero, a hero without an army, and more spells (by the way, notice that they are demanding the same thing from the fifth game now; maybe there should be more spells, but they should be completely different from the existing ones by nature). So, in terms of gathering information, I think the experiment with the fourth game was a complete success. But was the fourth game successful as a game? You know that yourself.