I have been wondering, instead of seven virtues heroes, why not Ten Commandments heroes?
Because they wouldn't be that different from each other. And the whole idea of such a theme is to make each person easily recognizable. You hear the sin and you can imagine the person behind it.
But for Ten Commandments?
The "Thou shalt not steal "-hero? Shouldn't that be all of them?
The "Thou shalt not commit adultery"-hero? So all the other 9 go and take random wives?
The "Thou shalt not covet thy neighbour's house"-hero?
There would be some cool ideas you could do with it (like a hero who rests on sunday even in the middle of a war). But that's where you take a good thing and make it a flaw.
But generally said, most "you shall be good"-rules are hard to use, because every hero should follow most of them. Otherwise they wouldn't be a hero...