It depends what hirelings ARE - are they really completely custom but limited characters that we collect on our journey (soul coins?) or do that have at least some amount of personality - custom VO barks, portrait etc.
If they are created fully using Tav’s assets, than limiting anything (including their number) seems rather unnecessary. A custom mercenary creator (akin to Pillars of Eternity) would seem like a simpler option - unless engine doesn’t allow for character creation once the campaign is going, and Larian opted for a workaround using the respec feature.
