Little late to this topic, but it's pretty good all around. It doesn't really prevent spaghetti ships but it definitely makes them more of a pain in the ass to build as well as a little less efficient. There's not really anything we can do realistically to equalize normal ships and spaced out ships without a shit ton of extremely serious code additions/reworks. Something is better than nothing.
Regarding how to quantify ship effectiveness, mass/block count is certainly the most accurate short hand way to tell what a ship is like. When you've played the game long enough, you can predict with reasonable accuracy how much of X Y and Z a ship has based on how much it weighs. In general most people build very similarly, and you can predict even more accurately if you know the player and their style of building. Obviously, the most accurate assessment of a ship would be its mass and block count (mass for general size, block count to compare how much and what type of armor), how much power generation and storage it has (with this you can guess what type of weapons they're using and roughly how large they are/how much damage they do), shield storage and regen including docked entities (how long it will take to drop their shields as well as if you can do damage at all + docked entity "tanking") as well as thrust (how effectively you can control distance).
That's a lot of information to list if you're not interested in writing a book in casual conversations. Ergo, most people simplify to just mass or block count, or both. Dimensions are very rarely used these days if at all for the simple fact of disparity between dimensions and mass, with mass being a far more important determination of what a ship is like - knowing how many blocks you have is more important than knowing how large they are at maximum on each axis.
As an example, I have two working ships in my catalog. Both of them are roughly 150m x 150m x 400m lwh. The first of them weighs roughly ~130,000, ~140,000 mass. The second weighs just under 5,000 mass. You see the disparity? That's a 28x difference, which is massive. I'd invite you to show me a 28x difference in anything between two equally massed, working ships.
Will a 1km long spaghetti monster consistently defeat a 1km long "normal" densely filled minmaxxed ship? (Not rhetorical, I'd like to know the answer and currently don't)
If not then you can't say that when balancing by length that spaghetti is meta.
FWIW I 100% agree that balancing ships by mass is a far better method than attempting to balance by dimensions - i.e. it would be silly for duel rules to specify max length/width/depth, or block count, instead of mass.
Very easily the spaghetti monster will win. In fact, I would be 100% confident in saying that the spaghetti ship won't even be hit by the normal ship. At 1km, you're able to fit in an absolutely absurd amount of power in power 1.0, beyond the realm of reason, if you have enough patience. You can push out an absolutely enormous amount of DPS, more than enough to erase pretty much any ship in the game. Shields don't even matter at that point - with a 1km^3 box to work with, you have enough space to ensure that hits from missiles damage only a handful of blocks and waste most of their damage into empty space, and even hitscan beams will only destroy a pittance of blocks unless the AI accuracy is enormous.
To put it into perspective - in power 1.0, a well designed 5,000 mass spaghetti ship can do well over 500,000 DPS. More than half of that is power, thrust, shields, tertiaries, etc - let's assume it takes us the full 5,000 mass per 500,000 DPS. Now stack it, since it stacks linearly, until you have the amount of DPS you want. See where this is going? 2,500,000 DPS is enough to handle 98% of ships I've seen under 500,000 mass. To do that I need only 25,000 mass - less, really, if I really wanted to be on a knife's edge of cheese, so to speak.
Do you guys see how this is a problem yet? The scaling for weapons and power generation so vastly outstrips defensive scaling it's not even amusing. The only defense against this sort of thing is just not to be hit, and how do you achieve that? Space your ship out, which you coincidentally already will do to achieve your power generation. It's a circular train of logic that's revolving around a very specific style of ship.
If anyone would like a demonstration, I'd be more than happy to set up something to prove I'm not just bullshitting. Or check out
my videos or
Veilith's videos - premise of these posts are put into action.