Think you that in the current basketball it is necessary préferable to work the strong hand both side of the basket or to work the weak hand? I notice that fewer and fewer right-hander uses the right hand lay up on the lef has high level. I wait for your reactions...
I strongly believe that the players have to learn to shoot the lay up with both hands. The teaching point is that a player should always have his body between the ball and his opponent to protect the ball. The chances to get blocked on a right handed fingerroll from the left side are pretty high.
The responsibility is with the coaches. You have to ask the players to use their weak hand as soon as they can make the lay up with their strong hand.