Add Name field on User Registration Page

It is very sad to say that, User registration page does not contain First Name and Last Name option. Even though, we can allow, firstname and lastname in #MyAccountDetails but not at Registration Page ?

We know, we can do this by something like, hooks or modifying page-register.php

Why not add in a theme option ? And if you insist me to add as registration-fields, there behaviours are odd. Look screenshot, what they, if I add them by custom-field in registration.

Can anyone give me the hooks or php code help to achieve, so that, I can use that name in email-template.