Your data will live for the next 30 years. Your UIs are replaced with every new fad. Do you think it is more important to thoroughly design your database or your client domain model?

Of course, projects are different, and some projects are more user-centric, others are more data-centric, but chances are that you're successful and then you'll regret working with a horrible database schema that you didn't properly design 5 years ago, cause all you cared for were your fancy foobarWidgets that you implemented in a tech that no longer exists...