Refunds during major updates

I have always wondered why Riot doesn't do this.

Each time their is a major update to the game (such as the tank or mage update for example). Give players 1 refund option so that they may try out the champ (if they do not own the champ). So that new players can try out new champs, and if they do not like the champ, they can simply refund them. I think this could be good for champion diversity in the player base and allow new players to explore new things. (btw i do not mean give people lots of refunds, but one or two refunds per year might be a good thing)

-Thanks :)