Which type of dice are used is really unimportant. What matters is the both players have the same chances. That is what makes the game fair.
There is no reason to buy the more expensive casino dice other than to buy an advantage. There is a clear standard for dice that wargamers use. Anyone using casino dice and not offering them to their opponent might as well be using weighted dice as the outcome is the same - having better odds than the person they are playing against.
Compared to standard dice, they have a higher chance of producing a, generally, favorable result. That is an advantage.