I would like to see different classes of torpedo of different diameters like that. I had an idea for a duplex torpedo, where the warhead is loaded first, and the propulsion section loaded second like the shell and propellant of artillery. It's just a way to get more torpedo into the standard size launcher. That's kind of a mid-step for hulls which can't handle a larger launcher firing wider and longer torpedoes.
One reason I used to enjoy the game Tachyon: The Fringe is that you could customize ships, and you had a nice range of options. You had four classes of rack (munition) weapons, although the faction you chose might determine what you could mount. GalSpan vessels tended to favor a lot of guided torpedoes and missiles, while Bora vessels couldn't mount those but favored rockets and sappers.
Each type has its own attributes, perhaps in part for game balance purposes. Torpedoes are guided and generally fairly reliable, but had a relatively slow lock and fire rate. Missiles are also guided and more general purpose, with their main drawback being somewhat limited ammunition. My personal favorite is the Swarm anti-fighter missile, a favorite of GalSpan, which fires a cluster of sub-missiles and is pretty nasty when it hits.
Rockets are generally unguided warheads, with the balance of being cheaper (so you can buy more of them for a single launcher) and mounting a larger warhead than a guided version (so that the damage range between most models is pretty close, or in some cases favoring the rocket). With a bomber type hull and a skilled pilot, a rocket array can be an excellent heavy weapon.
Sappers, with one exception, are not true warheads but are designed to drain energy from the target's hull, like from shields or weapons. The remote sapper is a bomb that can be triggered by the pilot, under ideal circumstances. The Bora colonies are primarily miners and modified much of their military hardware from engineering equipment. Some pirate groups have acquired sappers as well, though they're a less common weapon outside of Bora space.
Both guided warheads and sappers are vulnerable to defense systems which can counter them, if the target ship has them equipped. Guided ECMs will try to fool a target lock by releasing chaff to trick the missile, and sappers can be overloaded with a burn-off device. So there are options in both directions for a pilot to consider.