Scientific research on the mitigation hierarchy has steadily increased over the past few years at the international level. While some seek to improve the application of this public action instrument, others point out its shortcomings and risks. This opinion paper—which focuses on the French context—does not provide an exhaustive overview of existing research but instead targets specific issues considered to be a “priority”. We mainly investigate the relevance and implementation of the mitigation hierarchy, especially from an ecological point of view. Part of this paper thus questions the very principle of biodiversity offsetting (BO)—the last resort of the mitigation hierarchy that brings together numerous controversies—and the adequacy of the mitigation hierarchy with the objective of no net loss (NNL) of biodiversity. The general idea underlying this paper is to show how the mitigation hierarchy has been built and based on what values (mainly economic and legal, which leads us to conclude about the lack of ecology in the policy itself). In doing so, we provide a few perspectives as to what should be done to (better) integrate ecology into land use planning and development.