I think I already reported some of those on Jira, this issue came up before, but now that ITK Jira is gone, no way to confirm…
Based on a discussion here: Slicer DICOM Scalar volume plugin relies on (old) GDCM: why do we not use DCMTK? - #24 by pieper, looks like the “home” for ITK DICOM development is GitHub - KitwareMedical/ITKDICOM: Better support for DICOM in ITK., but I do not see a lot of activity there, and there are issues open since 2017. Not clear if ITK community prioritized DICOM support over many competing interests. I am sure something like “deep learning in ITK” would be much higher on the list! 