It sets the tone for the entire interview.
If you give a long-winded or irrelevant answer, you're sending the signal that you're not the right candidate.
If you mess this one up, you have to say SEVEN awesome answers to get back to neutral. And sometimes, interviews will be cut short if the first impression is not strong enough. Unfair, I know. But...if they think everyone is wasting their time, why wouldn't they cut it short?
If you can get this answer right, it'll boost your confidence and set you at ease for the rest of the interview. You can be deliberate about what you share and highlight. You can set the tone by nailing this answer.