If you don't know with mob grief off Villager breeding becomes REALLY hard because you have to trade with them for them to breed and even then it is only a 20% chance. There is a way to fix this, the reason why mob grief is off is to protect spawn from being damage from creepers and to help players from these lethal monsters. So mob grief off protects the players and spawn. There is a way to fix the creeper problem and have mob grief on so villagers will still plant and breed easy. You can use /entitydata on a clock to lower creeper's blast radius to 0, but that will also decrease the health damage they deal significantly:
/entitydata @e[type=Creeper] {ExplosionRadius:0}
Help the players that want to make there breeders and make farms easy and please try to get the mods to notice this post.