Pseudo fields provided by hook_field_extra_fields is something available in Drupal core. For that reason I believe we should not need an independent module such as Extrafields Views Integration to make them available in Views, especially now that Views is in core. This might already be the case in D8 so we might only need to backport this to D7. It's a great thing that this feature has been developed in parallel because it may not have been available at all, but now that it is I think it should be integrated back to Views core. What will happen if tomorrow this module is not maintained anymore and modifications in Views core break it? We should be able to use Drupal core features and expect them to work in Views.