I didn't explain that well. The problem really isn't that in in GC1, Civ3, and similar, there was a one-to-one correspondance between a battleship and the tech required for the battleship. and in GC2, there are multiple tech requirements.
The problem is, there are thousands of ships that could be called a battleship. There are thousands of ships that could be called a scout, or a survey vessel, or whatever have you. This makes it hard to say "Show me the techs I should research for battleship."
What's the definition of a battleship? Let's say that a battleship is a medium hull with a reasonable amount of offense and defense, enough range so that it can reach nearby enemy stars, and enough speed that it won't take forever to get there.
Let's see, since we need at least one engine, that means that we have 14 levels of engine we can put on it, assuming that we stick to a single engine. Each of those 14 levels would have different tech requirements.
Weapons: There's approximately 70 types of weapons.
Defenses: There's approximately 54 types of defenses.
Life support: There's 5 types of life support, not counting none.
Sensors: 6 types of sensors.
So, assuming that we only go for one of each, we have a total so far of 14*70*54*5*6, or 158760 (I think, did the math in my head) combinations so far. And all that is assuming that we went with one of each component. On a medium hull, we can probably fit more than one of some of those components, and if we've got lots of miniaturization, the number goes much higher. Now, most of those combinations aren't going to be seen, because people tend to level somewhat equally through the tech tree, but there's still enough valid and reasonable combinations that the numbers are quite large.
So, which of those thousands of battleships do you want to aim for?
Just at random, here's two ships that could both be called an early to mid-game missile/point defense battleship:
Medium hull, 3 Harpoon IIIs, one ECM III, a Warp III engine, two basic life support, and two sensor 2.
Medium Hull, 2 Harpoon IVs, 2 Smart Chaff, a Warp V engine, one advance life support, and one sensor 3.
One of these will probably require more miniaturization than the other, both require mildly different tech levels in several areas, but both are basically the same concept, just expressed with different technology at hand.
So, if you want something that tells you what tech you need to get a certain ship, that can be done, and that's what I described. What you need to understand though, is that games that think "dozens of types of units are a lot" are fish in a water trough, we're in the ocean here. Even if the devs provide 100 different battleships, odds are that none of them are going to be just right for the techs that you have in 90% of the cases.
The other thing that was suggested was to have an advisor that you could say "focus research on millitary" and it would pick relevant techs. Two problems there. First, it would need to know where you want to go. If you're expecting to go to war with a race using beam attack ships, the advisor would have to know this in order to make sure you researched shield defenses. In Civ3, there weren't a lot of parallel military tech paths like in GC2. It's not like you could focus research on infantry OR cavalry OR tanks. Because of the multiple prerequisites for techs, you'd have to go through contortions not to eventually get all the military units.
The second part is that the advisor would have to be sharp enough to know that if you have techs X, Y, Z, it can build a good ship, but if it upgrades X, it gets a different ship and if it upgrades Y or Z, still different ships, and it has to be able to understand when each of those different ships would be better. It would also have to know if you're planning on staying ahead technologically and using small ships, or if you've researched as far as you're going to in the short term, so will more likely be smashing the enemy with bigger ships.
In my opinion, doing something like the first makes sense provided we have a large library of ship designs and a reasonable way to select one we want from them. However, it's not critical.
The second part is an unworkable crutch. Players that used it would get more frustrated at loosing often than the ones that got frustrated learning how the system works, in my opinion.
