Hello

We already had multiple personal messages about this. NUTS regions actually coming from EU laws, they are managed by EuroStat: https://eur-lex.europa.eu/legal-content/EN/TXT/?qid=1412076854301&uri=CELEX:32005R1888

Commission Decision of 12 December 2011 on the reuse of Commission documents: https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX:32011D0833

For most other European countries  they are already mapped, I'm just finishing other's work.

> what added value does this data have for the OpenStreetMap project and wouldn't a uMap be better suited for this?

You can ask this about a lot of things, why add anything at all if you can just remember the location of things, or add it to umap... 

Added value is, we will have a complete map of NUTS regions on osm, not an incomplete one...