If we don't offer a do-it-yourself delete option and require that users submit a profile deletion request, it is a conscious decision, to deter potential hit-and-run mischief.
We have reasoned as follows: Why give some user the opportunity to send mean or malicious messages to their matches, deactivate their accounts (on their own, instantly), and disappear, without having to face any consequences for any abusive behavior on their way out.
And disappear they would once their profile is deleted, because all identifiable/contact information, is promptly flushed from our system.
Genuine users don't have to worry, though. We respect users' wishes and promptly act on profile deletion requests, typically within a day. And when a profile is deleted, it is gone permanently.
So, as counter-intuitive as it may be, our approach – of requiring that people submit a profile deletion request – helps to improve user safety and security overall, by enforcing good behavior.