Have you been feeding them a high nitrogen fertiliser? If so change to potash once they start flowering. (Tomato fertiiser is good)
Don't know if you can have too many leaves but wouldn't have thought so.

Saw the BBC new southeast earlier and the strawberries have loads of leaves and not much fruit due to the dire weather this year.

I now cut off all Strawberry foliage in Jan/Feb. That stops too much foliage and gives light for the fruit as well as extending the life of the plant.

Thanks