ACML 6 introduces many new dependent dynamic libraries (acml_bridge, clBLAS, clFFT, acml_script); the ACML backend is going through major changes right now, although we are doing our best to make sure the ACML frontend looks and behaves the same. Dynamic libraries gives us a more encapsulated way to ease into these major backend changes. We don't currently have plans to reintroduce the static libraries.
If we ship acml static libraries, your executable will still depend on our other dynamic libraries. ACML dynamically loads the dynamic libraries i mention above, so statically linking ACML only eliminates the one library; your executable inherits the other dependencies.