According to discussions we had both here: #4093 and in the ticket for now I went the easiest path, so just to make the persistence in the service layer.
I think doing data binding in the controller is not that bad, since in spring we also use @RequestBody to do it for us, but eventually in the MVP1/2 we could follow path of creating DTOs for those, so to make

User createUser(BasicUserDTO user) {
  ...
}
...
class BasicUserDto {
  String firstName
  String lastName
  String email
}

User createUser(UserWithDetailsDto user) {
  ...
}
...
class UserWithDetailsDto extends BasicUserDto {
  Date dateOfBirth
  Locale locale
  ...
}

but user is specific case. But I believe this would be still a better approach instead of extracting a lot of params and passing it to the service etc.
I'm looking forward to discuss it in the future.