If they were just less popular with audiences that'd be fine. But they're also not as popular with critics, at least in the long term.
The highest rated movies of the 2010s according to Metacritic were Boyhood, Moonlight, Roma, Manchester by the Sea, 12 Years a Slave, Gravity, Parasite, Portrait of a Lady on Fire, Carol, and The Social Network. The list of movies that appeared in most critics' lists were: Mad Max, Moonlight, Social Network, Get Out, Under the Skin, Tree of Life, Inception, Inside Llewyin Davis, Boyhood, and The Master. The only Best Picture winners from those two lists are Moonlight, 12 Years a Slave, and Parasite.
I only see two winners in the Letterboxd Top 50 of the 2010s (Moonlight and Parasite).
'Popularity' is hard to compare since it's two different decades and consumer habits changed a lot. But at least 5 movies from the 1990s were in the top-10 box office that year (Dances with Wolves, Silence of the Lambs, Schindler's List, Forrest Gump, Titanic) and outgrossed the most successful BP winner of the 2010s (The King's Speech) when you account for inflation.