Like what exactly? Not like the design we're currently discussing, it spaces the stabiliser and reactor far beyond what power 2.0 requires, so it obviously wasn't the driver for this type of design.
I haven't 100% been keeping up with the minute balance changes in the dev updates, but the stabilizer distances in 2.0 were pretty massive at larger reactor sizes. Furthermore, by NOT punishing this sort of design, it encourages it, as there is no incentive to NOT spaghettify your vessel.
So what this boils down to is that power 2.0 isn't responsible for a design like that working, designs like that already worked with the current power system.
No, power 2.0 is responsible for the design working within its confines. Power 1.0 has zero effect on 2.0. 2.0 should not allow these vessels to exist to begin with.
I haven't given fixing spaghetti meta any thought, but one idea that springs immediately to mind is missiles exploding based on proximity to a target instead of impacting the target - possibly as a separate subclass of missile. Have them explode when there's blocks in their blast radius.
This would be cool, but I don't think it would even do that much to fix the problems. Most of these ships run massive manual missile shootdown arrays, and missiles are entirely incompetent at tracking fast ships, even when they should have the speed to do so. Especially when that ship is far away or across a sector border.
You are attempting to treat the symptoms instead of the cause. We need to fix the power system so that spaghetti doesn't work.
EDIT: and although I don't actually know it, I kind of suspect SM doesn't apply realistic rotational inertia. Turn rate would be another good way to punish spaghetti.
Spaghetti ships already reach the maximum turn speed. Turn rate is not an effective balancing function on large ships when turrets exist and aiming cones for manual weapons are gigantic anyway.
I don't see why anyone assumes that a power update should be the fix to spaghetti meta. The power update didn't create this meta, they're independent of each other. It can have its own fix.
I'm repeating myself, but I don't see any reason why it should - a separate mechanic can fix spaghetti meta.
You are looking at things backwards. Flying spaghetti monsters are not independent of the power system. They are just variables of both power systems because of failures to properly balance them out. Both systems encourage the building style. We can and SHOULD fix the spaghetti by fixing the power system.
Here's my proposal.
Step One: Give a maximum range as well as a minimum range to stabilizers so there is a range they must actually be placed in to work. This makes it so the reactor and stabilizer must be a combined unit, making it harder to spread the ship out into spaghetti strands.
Step Two: Conduits should follow the resistance rules of real wires. Longer and thinner conduits should have increased resistance, reducing the amount of power that gets to their system. For an average normal ship, which might be roughly 30x30x300 and weigh a few tens of thousands of mass, this isn't a problem as they can just make their conduits a little thicker for their systems on the absolute far end of the ship. For a 30k mass spaghetti ship that might cover a kilometer and a half, however, this is hellish abuse on power efficiency or on their thin profile when they need to make their conduits into 10 meter thick columns to cross such a vast distance.
Step Three: All systems (weapons, shields, thrusters, turret docks and enhancers, etc) should require a conduit connection. This is the final nail in the spaghetti monster's coffin, as it can no longer rely using gulfs of empty space between each individual thruster and shield. Each system group would need its own thick conduit leading to it or it will have to rely on "wireless power" which will have heavy debuffs or efficiency loss, and if they have to lead conduits to all their spread out groups in the first place there's no longer a reason to build spaghetti, because it's become so solid with conduit lines that it would be more efficient and "meta" to just build a normal ship.
That's just how I would fix it from the power perspective, of course. I would also like to see things like NPC crew and weapon changes (like your proximity missiles), to help further it and make regular ship building and combat more interesting in general, but I think the power system should be able to stand up to spaghetti on its own without needing to rely on the fickle shifting of other systems.