The problem is only a handful of Kelvin type ships had any external features large enough or in the right place to b torpedo launchers.
Why is this a problem? We never see any of those ships fire torpedoes.
We never saw Saratoga fire them either, but we know she had them. I expect them to be standard equipment on all Starfleet ships, but not necessarily with a standard launcher.
Invoking the various sizes and calibers of guns is just splitting hairs
It's less so than dividing torpedoes into warp-capable and warp-incapable.
With the exception that the two designs will use COMPLETELY different propulsion systems; that's like saying cruise missiles and torpedoes are the same thing.
Today, the average warship has a 3in "dual purpose" gun that does everything from shore bombardment to AA to warning shots to sinking thine enemy to illuminating to saluting, and sometimes fires guided projectiles as well.
Indeed. Because GUNS have been replaced in most niches by various types of missiles and rockets and even fighter aircraft that can do the same job more effectively. Instead of an arsenal of various guns, a warship carries an arsenal that INCLUDES a gun. Weapons technology grows more and more diverse, and is set to do so again if and when laser-based weapons come to replace gun/missile CIWS.
That's how naval hardware naturally develops: the less variety you have, the less unnecessary weight you have to carry...
The reason for the increase in variety IS the reduction of weight. As newer weapon systems become more effective they also tend to become smaller, which allows addition of other weapon systems to increase the ship's capabilities. So instead of having to carry 40 machineguns and 20 40mm cannons to protect an aircraft carrier, a cruise (or even a battleship) can shed those weapons in favor of a pair of missile launchers, freeing space for other weapons like lighweight torpedo launchers, anti-ship missile launchers, cruise missile launchers, decoys, chaff, jammers, more sensors, radar-guided CIWS, etc. When a single weapon can do more work, you need fewer weapons of the same type to do that same job.
By analogy, think of Starfleet's hand phasers. Most times, a pistol phaser will suffice even for heavy combat duty; if you don't have to carry around a phaser rifle, then your crew can carry tricorders, medical equipment, the [tech] of the week and all sorts of other stuff that might be useful on their mission. The tricorder, too, adds some functionality; a single device that does alot, and therefore frees you up to carry more devices (or none if you prefer).
That's how technology progresses: when functionalities are compacted, you gain "slots" to add more functions. This has even happened in personal computing: processes become more powerful, computers have more processing power to devote to individual tasks, and the diversity in applications and functions increases dramatically. Thus you have room for more, you ADD more. When you find a way to shrink your torpedo's guidance system or propulsion section or even make the warhead smaller, you can make the torpedo more powerful/accurate/maneuverable for its given size, or you can make the same torpedo smaller and free room in the magazine for a starship to include fifteen other weapons that have capabilities a normal torpedo doesn't have.
Today's missiles are still pretty primitive and incapable of the same sort of flexibility as modern, mature guns. A modern destroyer would nevertheless do well to only stock SM series missiles, which could easily sink surface vessels or hit shore installations (the ARM is just a Standard with a different seeker), and could probably be modified to replace the more or less useless ASROC, too.
Modern, mature guns cannot shoot down jet aircraft OR cruise missiles with any degree of reliability. Nor can they engage surface targets at long ranges. Using them to launch torpedoes as in ASROC would be a bit silly since the only purpose of the system is to fire an unguided rocket carrying a torpedo to a specific distant location.
But everything the Standard does well, there is at least one other weapon in the Navy's arsenal that does it slightly (or ALOT) better. That means you need fewer standards to defend the ship than you otherwise would and you have more room for other weapons that have superior functionality in those respects.
Steps in that direction are already taken anyway, with the replacement of multiple launcher types with just one kind of swinging arm or VLS array.
Exactly: a single LAUNCHER, for a dozen types of WEAPONS. Same thing I had in mind for Starfleet's torpedoes. We already know there are a dozen different launcher designs in the fleet, but we've only ever seen two types of torpedoes. That seems counter-intuitive.
We consider it natural that the entire world is being concentrated on our palms: phones, computers, typewriters, fax machines, notebooks, wallets, bus tickets, mailboxes, music players and still and video cameras are one and the same device now.
Which necessitates the development of iPads, 4G wireless cards, portable routers, portable chargers, compact HD cameras, headsets, eyepieces, tablet computers, etc etc. For every five devices you compress into a smartphone, five more come up and take its place; and yet, most people DON'T go the smartphone route and still prefer to use one freakishly powerful device that does exactly what they want it to and does it extremely well; hence iPod sales remain strong even in the age of smartphones.
Of course, focussing development on iPods mean iPods can get smaller while still increasing storage capacity. This leaves more room in your pocket for that smartphone if you need one, and maybe a FLIPcam if you're wearing cargo pants and have discovered the hard way that HTC makes a crappy camera.
You don't want the shotgun specialist or the squad support LMG specialist in the platoon today
Says you. The Army seems to think otherwise. They have apparently discovered--as you have apparently forgotten--that you cannot shoot the lock off a door with an assault rifle. They tried to build this functionality in the M4 carbine with a special soft lead round that would duplicate the functionality of a breaching shotgun shells; that was a rather enormous disaster.
Incompetent engineers, stingy employers and greedy manufacturers may not be able or willing to give it all to us in a single package yet...
There's nothing incompetent, stingy or greedy about acknowledging the need for specialized equipment. General purpose equipment has its uses, but cannot fill ALL niches all the time. Modularity is popular with designers right now, though, because it simplifies the one and only problem with specialization--
logistics--while preserving the advantages OF specialization.
