Hollywood just haven't used her right
Can you name a film she's done stateside that you would consider she's done that's come near her French work. It's a tough one
Love at her French C.V, La Vie en Rose, Rust and Bone, Love Me If You Dare, Little White Lies, Two days one Night, A Very Long Engagement and Innocence.
Looking at her English speaking roles that really stand out, I thought she was good in The Good Year, Midnight In Paris, Inception, The Dark Knight Rises, Macbeth (her best English speaking performance imo) and underrated The Immigrant.
Some great work in those Hollywood films, but has she really given a performance in any of them that rival her French work. I don't think she has, some might disagree with me on that. Maybe it's her choice but I love to see her pull in some top performances that rival her work in French cinema.