I think the default ships being underpowered or just plain stupid is by design. I would, however, LOVE to be able to upgrade them so I can use the same visuals, at least for the non-military ships.
Given the way defenses work (defenses that don't match the attacking weapon type are only effective as the square root) I think spreading out offensive capability among defensive ships makes perfect sense. And since defensive ships don't need any extra propulsion, there's certainly room for more weapons.
Shipyard refits, i.e. instead of paying cash to "upgrade" I can have a shipyard do it using military production. In Diplomacy, I'd like see a "What will you offer me for this?" option along with a "What do you want for this?" option. Also, when trading technology, offering a technology that has prequisites should add the prerequisites they don't have automatically; and they should be removed as a group too. I don't like the AI complaining that I don't have the technologies straight
