Is that confirmed?
I agree on exterior customization but would you not have one of the most advanced ships from the Milky Way already? I guess if there is new Andromeda tech you could add it would work. I was just really referring to Ryder's personal quarters being customizable and have it be minor stuff.
Nothing about this game is confirmed, other than we are in the Andromeda galaxy, the mako is back, and we are a human protagonist somehow affiliated with the N7 program.
My only reasoning for this is concept art that looked like it was of the ARK was suggested by BioWare as being a "social hub," meaning it wouldn't be our own personal ship to traverse the galaxy in. Besides, the ARK is far to large to joyride around Andromeda. We need something the size of the Normandy in order to sneak in undetected.
We actually don't know anything about our new ship other than it might be called the "Tempest," if you believe unconfirmed leaks. We can assume it may be based off the same technology that powers the ARK, but we honestly don't know. Heck, it might be a hunk of junk, like the Millennium Falcon, and one of our tasks is to repair and upgrade the ship in order to traverse the Andromeda galaxy.
Assuming we are "Ryder," which I'm not convinced we are, I never saw much purpose in the personal quarters. We could feed fish, change our outfit, or turn on some music. While being able to add more personal touches would increase functionality to some extent, I'd rather the personal quarters have some tangible use. I'm not sure what exactly that would be, as Skyhold was largely worthless when it came to the Inquisitor's bedroom as well. You could change the drapes and design of the castle though. I find that to be largely fluff content and nothing else.