It's nice that they're testing how new users, preferably those who have never seen a computer before in their lives, react to UIs and how quickly they discover new features.
But what about all the existing users, who know the app and its features and who are really annoyed by these "modern" HUGE UIs that waste 60% of screen space with some jumbotron and hide all other features behind menus (or downright remove them) because "they might confuse new users"?