The reason is that DSLs are just viewed as "another" burdensome language, instead of a design for codified problem-specific knowledge. A DSL should evolve as we evolve our understanding of the problem. Think about successful DSLs like Mathematica, for example.
I've seen lovely crafted DSLs that were deemed unmaintainable when the creator moved on, and management cursed the use of them if they weren't already a popular OSS project.