Why would you switch weapon mid hunt?

As you had only one weapon at hand in previous Monster Hunter games I need to get my head around why you would switch weapons mid hunt, worked some scenarios out and one doesn't make sense to me.

  1. You don't switch. You have a secondary slave weapon only for the skills and use only your primary weapon.

  2. You have a copy of your primary melee weapon. That way you do not have to switch playstyles and have double the sharpness.

  3. As a melee main you have a gunner weapon or insect glaive as an anti-air weapon. E.g. as you hack away on Rathaloses feet with your Greatsword it lifts off, so you get a bow out to shot it down.

  4. You have two gunner weapons. You either switch between a close range and a far range weapon or one weapon is better in one ammo type and the other one in another one.

The scenario I can't get my head around is if you main a gunner weapon, why would you switch to a melee weapon? Maybe to cut or break parts? Maybe if the monster needs to be fought in a to close range?

Are there other scenarios why you would switch weapons mid hunt I didn't list?