Since the slower hulls don't really get anywhere quickly to begin with, slowing them down more doesn't really hurt them much anyway, especially when they become harder to kill off. The speed penalties only really make a difference when a certain ship would take more turns to reach a particular destination than if it had no speed penalty
On the contrary, speed penalties hurt the slow hulls much more than the fast ones.
First of all, it already takes them ages to move around, slowing them down even more makes using them annoying, un-fun and even micromanagy, especially later in the game when you have a bigger empire and the distances your fleets have to travel increase. The result are fleets that take many turns to get from A to B, requiring the player to carefully plan and manage a whole lot of fleets moving around, keeping in mind which fleet moves where, which defensive or attack positions do have already enough reinforcements en route and which don't. The longer it takes your fleets to get to their destinations, the more of them are in transit at any given time, the more difficult it gets to keep track of everything. Even if you balance things in a way that these slow, but heavily armored ships are still a viable strategic option, players might get discouraged from actually making use of that option because it's so much more work to handle it, that you end up killing this option off.
Secondly, as the speed penalties are implemented as fixed numbers, slower hulls suffer more from them because proportionally their speed is reduced more. Example:
We have two hulls, hull A has speed 100, hull B has speed 50. If I reduce A's speed by 5, that amounts to a speed reduction of 5%. It will travel a distance of 1000 in 10.53 instead of 10 turns, that's an increase in travel time by 5.3%. If I reduce B's speed by 5, that amounts to a speed reduction of 10%. It will travel a distance of 1000 in 22.22 instead of 20 turns, that's an increase in travel time by 11.1%. A hull with half the speed is hurt twice as hard by the same absolute speed reduction.
I believe the original intention was to allow ships to move around the map quicker mid-late game. The option of negating speed penalties is just a side effect.
IIRC they were introduced together, and giving the player an option to negate the speed penalties of armor was at least as much an incentive for introducing engines as to be able to move ships around faster, not just a side effect...
The result is:
- You can build cheap assault ships that are fast, but have low structure.
- You can build powerful, but slow ships for defense (you can even design ships that are unable to move).
- You can build expensive ships that combine both (speed and high structure).
I haven't tested enough to decide whether the system is balanced and all options are viable, but from a design standpoint this all makes a lot of sense to me.
Not really. My problem is not that I'm against this kind of game mechanic in principle, what I dislike with this concept as it is implemented now is that it's inconsistent/incomplete/arbitrary. Let me explain:
Most the points you've made could be applied e.g. to weapons as well. Why not have big, heavy guns come with speed penalties too? This would require the player to choose between heavily armed but slower, and lighter armed but faster ships (or extremely expensive ships that are heavily armed and fast). And while we are at it, why not have all ship parts come with a certain amount of speed penalty, depending on how "heavy" they are? Ship parts like nova bombs could come with a very big speed penalty, which makes sense as that is an extremely powerful ship part (BigJoe would call it "epic"), whereas sensors might only have very light speed penalties. That would be more consistent.
But just picking armor for that kind of mechanic is what strikes me as completely arbitrary. My point being that this makes an exception to a consistent concept. The concept that speed is an inherent property of our hulls, and not provided by dedicated ship parts (engines). AFAIK there has been some extensive discussion on that in the past, because apparently there have been people who were strongly in favor of making speed not an inherent property of the hulls, but using engine ship parts for that. Obviously the final design decision had been against that concept, and in favor of having "engines" as an inherent aspect of "hulls".
So speed is now an inherent property of hulls, which have slots where ship parts can be placed to customize the basic hull types. The tradeoffs the player is confronted with when designing his ships are the cost/effectiveness balance of the various ship parts, the function they perform, and the limited amount of slots, which forces him to decide wether to put on an additional piece of armor to get a more durable ship or another gun to get more firepower, as Dilvish already pointed out:
You comment about armor being cheap, but all parts have comparable cost; the real cost for armor is the foregone weaponry.
Or maybe to put on some ship part that raises stealth to build a surprise attack ship, for the price of not being able to use that slot for neither armor nor a gun.
And that's how complex the whole ship design should get, to stay true to the KISS principle (AFAIK, these discussion happened before I joined the project). At this point I probably should admit that I would have been very much in favor of having engine ship parts providing a ship's speed, not having that as an inherent property of hulls. But the decision has been made, and I'm in favor of sticking with it (unless there are very compelling reasons to rethink that decision). If we constantly question finalized design decisions, we'll never get anything done, because there will always be good reasons why this or that can be done differently.
But sticking with a decision means really stick with it. And here's why I feel uneasy with this whole armor slows down ships thing: It introduces an exception to this concept, it kind of "breaks" it - because it's doing it arbitrarily only for armor, while everything else works according to the original design. Resulting e.g. in the problem how to balance the speed penalties without hurting slow hulls unproportionally (see above). This will be hard or even impossible to balance without getting even more complex (by making the speed penalties proportional to the base hull speed).
However, if we decide to introduce this kind of mechanic (heavy ship parts slowing down the ship), we shouln't do it halfway, but consistently and thoroughly. Then each ship part should impose a certain speed limit, and engines provide a ship's propulsion. More engines -> faster ship, but less slots for other stuff. Stuffing a hull to the brim with ship parts provide more power, but slows ship. Ship parts of the "epic" kind (like nove bombs) could be especially "heavy", that is, impose a speed penalty that requires several engine parts to get a movable ship at all. Thus requiring a hull with a sufficient number of slots to carry these uber-heavy epic ship parts (otherwise you end up with an expensive, immobile piece of ship that's most probably of no use at all). Effectively eleminating the need to add an additional slot type to restrict "epic" ship parts to "big" hulls.
There can definitely be said quite some things in favor of such a system. If
we decide to go all the way to a revised concept. But please don't keep the current mechanics and just plug in something that doesn't really fit with the rest because we were struck with the idea to balance armor by means of a different mechanic than all the other ship parts. This adds the complexity of that additional mechanic without getting all the benefits it could offer when applied to the whole hull/ship part concept consistently. Which would be decidedly anti-KISS IMO.
I hope I've been able to express my concerns sufficiently understandable...