The artist you're referring to is Sara Poyzer - https://m.imdb.com/name/nm1528342/ - she was replaced in one specific way:

The BBC is making a documentary about someone (as yet unknown), who is dying and has lost the ability to speak. Poyzer was on pencil (like standby, hold the date - but not confirmed).to narrate the dying person's words. Instead they contracted an AI agency to use AI to mimic the dying persons voice (from when they could still speak).

It would likely be cheaper and easier to hire an impressionist, or Ms Poyzer herself but I assume they are doing it for the "novelty" value, and with the blessing of the terminally ill person.

For that reason I think my point still stands, they have made the work harder and more expensive, and created a negative PR storm - all problems created by AI and not solved by.

You are incorrect that AI voice contracts are common place, as SAG negotiated that use of AI voice tools is to be compensated as if the actor recorded the lines themselves - which most actors do from home nowadays, so again it's at best the same cost for an inferior product - but actually more expensive because you were paying just the actor, but now you're paying the actor AND the AI techs.

edit: and not just that, AI voice products are bad. Yes, you can maybe fudge the uncanny Valley a bit by sculpting the prompts and the script to edge towards short sentences, delivered in a monotone, narrating an emotionless description without caring about stress patterns or emphasis, meter, inflection or caesura, and without any breathing sounds (sometimes a positive sometimes a negative) - but that's all in an actors wheelhouse for free.