I'm not an avid follower of rugby. I'm not sure if it should be changed as I think the weather should have an affect on the game. Teams from certain areas may have an advantage, but it is on the coach and the team to prepare for these situations. If you play an outdoor sport then you should expect the conditions to be less then ideal.

Even if the ball is changed weather could affect the field conditions and the team that practices under those conditions will still have some type of advantage.