•A weakness of Mass Driver that often isn't mentioned is that it is blocked by oncoming fire (although under some circumstances I seem to recall it isn't blocked.) So it is less useful against swarms.
•Your version of Mass Driver, is essentially, a sniper weapon. An obvious weapon archetype, the absence is suggestive. It does energy gameplay where the player runs away all game and gradually whittles down the opposition. The addition of such a weapon might be counterproductive. However, your point that it is useful against fleeing ships, is a good point. Some thoughts, if we can kite the enemy, then isn't it fair that they can kite us? (Yes) If it is fair, is it fun? (No). How can we stop kiting? Long range accurate weapons (e.g., Drak's Mass Driver), increased player speed (afterburners), cloaking, allow enemies to retreat out of map, decreased enemy speed, remove fleeing logic from enemy ships. If we have a weapon that can hit a fleeing target, then the target shouldn't bother to flee (the ship will eventually die, so the best solution is to attack and hope it can kill you first.) Therefore, I think the best solution might be to get rid of the ship fleeing AI and actually make things more aggressive, or to work in packs better. Thus the situtation where the Raven runs away is gone. Should the Raven be able to kite you at its max optimal weapon range, like an overgrown Hypersonic Pod? Not sure.
-That weakness is why I chose Mass Driver as the sniper weapon. Like real snipers, the best defense is cover. Spreadshot becomes the ideal form of that cover (hence the 360 degree spreadshot.) You can also dodge if moving at high angular valocities relative to the attacker (again the normal means of closing on a sniper).
-As for kiting: Kiting is, as you say, boring. It makes for long dull fights - alla Burlust Duels. Hence the need for a counter to the kite - alla Mass Driver...
-End Result: Mass Driver now has a CLEAR and DISTINCT purpose.
-Making spreadshot 360 degree comes from my acceptance that when surrounded, any limited arc version of spreadshot becomes 360 degree by firing at alternating targets anyways - but it becomes more focussed in less swarmed settings, which is what allowed it to dominate the DPS (it focussed or spread as needed, always delievering near maximized damage, despite the fact that DPS was balanced with the idea that many shots would miss), whereas always being 360 at set intervals means it is basically worthless against a limitted number of targets, but can still perform its primary defensive purpose of mass driver (and scrap/little craft) screening. So now it requires careful positioning to use offensively, but when such effort is (sucessfully) employed, it can quickly become a devastaing weapon. It now has a CLEAR and DISTINCT purpose.
•Comments on Minigun, Mass Driver, and Spreadshot - Swarm experiences tend to just be a couple of ships. Sure you can have the rare occurence when you are amidst 3 squadrons just after launch, but they die so easily, it just isn't a problem. Most of the time, to me, I have to kill 2-5 ships and the biggest problem is that they dodge my shots. Hence these weapons are all "standard duty" weapons. I just need to hit a few targets a couple of times to get rid of them. Medium and Small ships are almost the same in terms of danger, I don't treat them that differently (except when they have damage modifiers).
-In my expereince, swarms come about in one of a few ways.
1) Several flagships (in different areas of the battlefield) all launch smaller craft - instant swarm.
2) You are taking out stationary defenses - as "towers" are already in a "swarm" configuration if you punch through to the structure. (A swarm setting of your own making, but that's the whole point...)
3) Planetary Defense Missions tend to quickly become swarm settings, as flagships replace fallen comrads and disgorge more smaller craft, the smaller craft quickly start to pile up (and swarm) if not dealt with.
Each of these situations result in your becoming surrounded by several (not just 2-3) ships at a time.