KGB,
It might take a hero's presence to convince an army to march into dark caverns populated by horrible monsters.
Piranha,
If defeating a ruin is just another stack battle, I will just keep on pumping my heroes' command ability (which is all I do now). It would be nice if a ruin demanded your hero to be more of an adventurer and less of a leader....this would force a player to specialize a hero in one area or the other, or to make a jack-of-all-trades hero (which wouldn't be an exceptional leader or adventurer).
If a ruin was a one on one battle between the ruin's guardian and the exploring hero, players would be encouraged to buy strength and critical strike (and perhaps other combat bonuses yet to be available). I don't think that these are worth taking at the moment, so this would be a positive change.