I think the issue is that arrays directly map to low level C objects, and since the memory layout of an array is basically the same between Julia and C and copying the memory would be an unnecessary expense they just provided library calls to get at the array’s data.
With a Dict object that is an object created with Julia code, there is no C equivalent of a Dict. If they where to provide a C API for the Dict, then why not IOBuffer or RegEx? Where would the “line” be?