What would you change in Heroes of Might and Magic IV?

Regarding capturing a mine with an army without a hero, I don't have any ideas. As a flight of fancy, I can only suggest this: the hero-less army marches to the outer tavern and hires a hero. Or, it picks up a tomb on the map, goes to the Haven, and revives a hero.

Yeah, it's definitely far-fetched:D because in that scenario, a hero would still capture the mine... but here, the option is without the participation of a hero, ABSOLUTELY.
However, I didn't say that the mine needs to be captured; I said that they can gain control of the mine for the kingdom. In general, creatures cannot capture a mine, but they can BUILD it from a resource deposit, and it will then come under the control of the kingdom.;)