On 30 May 2020 I sent the following message to the NI Department of Health:

Thank you for making the COVID-19 dashboard available.

Are there plans to make machine readable downloads available, for
some of the data at least?

The dashboards for England, Scotland and Wales all have the
ability to download a spreadsheet/CSV.

Thanks,
Tom

I got a reply on 2 June 2020:

Mr White

Thank you for your query. Currently, the information on which the dashboard statistics are based is being drawn from live systems and the data is continually being revised. This means that we do not at this time feel it would be appropriate to provide data that is still volatile and is subject to both revision and change.

Regards

Information and Analysis Directorate

Needless to say, this is not a very good reason: all the other UK nations provide machine-readable data even though it is "volatile and is subject to both revision and change".