Allowing people to design interiors could be BIG for STO. It's not really a Star Trek thing but it is a MMO thing. It would sell a lot more Lifetime Memberships. Take Star Wars Galaxies, total customization of room interiors. Some players sold their services to be interior decorators from what I heard.
A few months back I put together an extensive proposal on revamping the ship interior to be both customisable according to class, size, decor etc, as well as making the customisations relevant to gameplay as a whole (boarding action, feature episode missions that use a player's ship customisation to tailor their playthrough experience):