There is no earthly reason why a solo string instrument or voice, having the possibility to play or sing pure intonation, should want, or try, to be tempered.
Sometimes, when you work with directors who have done it a lot and are established in the business and know the game, there are all these rules that they have. First-time directors will allow you to come in with choices. They're not so jaded by actors that they're like, 'Ugh, just do your job, man.'
As long as ugly people are not on TV, you should only ever have interesting people on TV.