The optimistic assumptions I have read about this particular conversion is that
- Perhaps 25mm Ammo is relatively plentiful in current stores (thought not manufactured since 1984)
- Increased elevation allows interception of drones (though ammo is not proximity fused)
- Up-gunned for urban warfare
- A feel good weapon for masses of cannon fodder (added in edit)
Or they are simply scraping the bottom of the barrel.
Edited ammo info after getting more information.