If you want such functionality you could implement a user registered handler and write your own code to do that.
However sending passwords in email is generally not considered a good security practice. If a user needs to recover a password it can be done but it is wise to then force them to change to a new password that has not been sent in an email. It does not seem like a good idea to send it right after user registration since that is a security risk and the user already knows the password and has not asked for it to be sent.
Also if configured for hashed passwords then we don't even know what the password is so we cannot send it. With hashed passwords in password recovery we must generate a new password for the user and send that and then require them to change it again for best security.
Also consider that if you use the Janrain Social sign for user registration the user does not need a new password. In that case we do populate the pwd field in mp_Users table with a random generated strong password because we have to populate it with something but the user does not need to use this password, they login using their credentials from an external provider whose password is unknown to us.
I will log a feature request in our project tracker for an option to send an email when creating new users manually since it does seem reasonable in that scenario. For now you will have to do that step manually. I recommend if you do that to also check the box to require the user to change the password after they login.
Hope that helps,