As for the Vegans, and your comment... "rubber-suit" is a term to describe making aliens that look different, but act just like humans.
In this case, what was proposed was that the Vegans incorporate their own culture into their ship designs, rather than copying Vilani or Solomani designs that don't reflect Vegan cultural norms!
Therefore, it is Vegans acting like Vegans... which is the opposite of "rubber-suity"!
They are NOT "aliens who do X for no reason", but "aliens who do X because that fits their described culture"!
There's two points I'd like to address here:
"Rubber-suity": This might be my personal viewpoint, but having Aliens who do X for no reason seems a subset of the rubber-suit concept - trying to differentiate them from humans without any thought to why they do what they do. Aliens like these are seen in spades in Star Trek and Star Wars. I guess the Kafers in 2300 AD would be the antithesis of these - they have a very good reason for doing the odd things they do.
Now the reason I see modular and subdivided ships as being rubber suity is that I have a background in Physics and Engineering, with an interest in naval and aviation affairs. To me both ideas seem like a recipe for disaster:
Modular ships will be heavier and thus lower performing than an integrated ship designed to the same task. They will also be at much more risk of losing vital systems when damaged - as the couplings between modules would be at risk of shock damage as the ship flexes more.
Compartmentalised ships will need extra crew to facilitate communications between the segregated sections. In an emergency they will not perform as well together as a ship's crew should.
Ships are built to do jobs well, within a budget. There are operational requirements written up as to the tasks a ship has to do in most (if not all) navies. There will be differing design philosophies - but they will not (knowingly) work against the efficiency of the ship. Budgets are set by governments, operational requirements by navies or other services (or by owners in the civvie world). I can't see why the Vegans would be any different - especially as they have an implacable enemy in their neighbourhood.
Who would set the budget for the Vegans? The Civil Service Tuhuir. Who would decide the Operational Requirements? The Naval Tuhuir (or the Scout Tuhuir, or Merchant Tuhuirs). Who would design it? Whatever Tuhuir is into Naval Architecture. Build it? Whatever Tuhiur is into Ship Building (or perhaps Naval Architecture and Ship Building are in the same Tuhuir). Who would 'man' it? I'd expect it to be crewed largely from the Tuhuir which drew up the Operational Requirement.
Look to the requirements and you'll find the ships the Vegans will want to build, though quirks will come from design requirements. For the former there's the enemy at the gate for the navy - and the fact that the Vegan Autonomous District is a large J-1 cluster. For the latter you can let your imagination run wild (within limits). Case in point: the USN and the RN did a study where they each designed a ship to a common operational requirement in the 80s. The US ship came in 1000 tons heavier than the UK one - mainly due to design requirements - the US ship's vital spots had to be designed to operate even if the area of the ship they were in was knocked out, the British though any hit capable of knocking out an area would knock out the vital spots in those areas. US diesel generators were also heavier than the British equivalents.