Drupal has always been criticized for its difficulty in creating truly good UI/UX, especially Drupal 7. In Drupal 8 this is considerably easier with the new twig engine. Even then there is a limitation to what we can do with the UI/UX. Don’t get me wrong, Drupal 8 backend is a godsend; extremely flexible and extensible. But to actually get that much flexibility in the front, we have to decouple.