I'm supportive of continuing this trend of relaxing restrictions - we saw that doing this with Master rank had very few negative consequences. Ultimately, granular mechanical ship size matters very little when it comes down to how much punch a ship packs in actual combat, and I feel like it would be completely good to soften the focus on nitty-gritty mathematics.
I would disagree, the size of a ship is very important when it comes to how much punch a ship packs in combat. A 500m ship will pack a significantly smaller punch when compared to a 2km ship which packs a smaller punch than a 5km or 10km ship. I don't disagree that the consequences might not be dire, but lets be fair, Darth Vesper, there is a lot of difference when it comes to combat.
Like Gil said, star destroyers are meant to be "ships capable of destroying entire star systems with their heavy firepower" (x) This is an awesome level of firepower to put in anyone's hands, and at the same time, a massive logistics load to manage. On Chaos we set those same Star Destroyers at 2000m. There is no way that your average individual is able to sustain control of the ship, or supply it by themselves. Like Gil said, only the largest corporations or governments can do that. And I think only Major Factions, governments that span multiple star systems can have more than 1 Star Destroyer.
So if we come back to the example from Captain Larraq, Admiral Fancypants. If he wants to tell the story of the admiral just flying around with his crew fighting NPCs then no-one is going to care. But the moment other PCs get involved, he might be asked to sub his ship to the factory, and needs to explain where his funds and crew are coming from. As I said before the factory is entirely optional, until it isn't. As people have pointed out, it's very easy to form a minor faction, and if Admiral Fancypants did that he can fly around in his ship to his hearts content. But just the one SD.
The Minor faction system is an issue for another time, but given how easy it is to justify and let people tell their stories there is no reason to change the rules. If you want to just tell a story then go ahead, I can't think of one person I know who is going to complain about that. Get a few friends and blow up all the NPC pirates you want. But if you want to fight other people, the rules we have exist to balance that system. There is no way an individual person has the resources to match a minor faction's fleet. Just as there is no way a minor faction can match the fleet of a major faction. By relaxing the rules on ship size you're adding an element of chaos into PvP that can be fraught enough as it is. If anyone can turn up with a Stardestroyer, then you're going to see a proliferation of them in PvP. Now I get that fleeting is a part of the play enjoyed by a small element of the community, but the way the rules work now, people can play with their big ships, they just can't attack other people with them without grounding their ownership in something explainable, which really isn't that hard to do.