All sailing ships rely on having their masts and sails in positions that give them a balanced and evenly weighted push from the wind. Bomb ketches are not handy sailing vessels, thanks to their compromised rigging and the weight of the mortar and its mounting. The design needs to keep the forward portion of the ship clear for firing the mortar.
The strength of a bomb is in its mortar. This can throw an explosive shell high into the air to plunge down on enemies. The fact that the shell is explosive rather than solid adds to its deadly qualities: men and structures are equally shredded by the arrival of a shell.
Duty aboard a “bomb” was not an enviable posting, and there was a good reason why bomb ketches were named after volcanoes, fire-gods or fearsome ideas. They had a nasty tendency to explode, thanks to the shells that they carried; fire aboard a mortar was far more dangerous than aboard any other type of sailing ship, as the ammunition as well as the propellant powder could go up! Despite this, all navies found them a useful ship to have, and the original French design was soon copied by all the sea-going European powers.