I think heroes should not come automatically, and meaby that there should be a set amount of heroes in the world, Not saying that I agree on the current concept, though I like it to be half the way heroes are recruited, much more important it would be nice to see the eventual reward of a hero from quests, or heroes arising after doing epics battles.
I am not much of a fan of the Tavern approach of the Heroes series, in which you have a special building to lure heroes out of they're caves or whereever they are hiding when not in plain sight
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I liked the part in Master of Magic that sometimes a hero had heard of your empire, and simply travelled into your empire and asked for employment.
I also like the thing that happens in the total war series, (some of those I played), sometimes after major battles, it seemed one of your soldiers proved valuable, honorable and most of all skilled enough to become a general, or said hero.
Sincerely
~ Kongdej