"So, I would prefer to keep the 3 stars cluster and mortar, but limit their ammo to 1, maybe 2 for mortar."
Personally, I really like the fact that you have another option for killing far away worms and destroying crates. Carefully adjusting mortar is also fun, and in some situations better than bazooka or grenade. Reducing ammo on these really takes some of the "we have no more ropes and we have a fierce long-distance exchange" away. There are many, many options to harm someone close range, dynamite and its variations, axe, well placed petrol, flamethrower and minigun.