I agree. This feature should have been in nopcommerce version 1.0 and there is no excuse for it not to be there.
It is not a good user experience if a user has to wait for an admin to resend an activation email.
When a user goes to a site it should be a streamlined process so that the user stays on your site and not go to a competitor.
Please implement this a default feature as soon as possible or show us in the meantime how to implement it in code.