Asked on Radio 2's Doctor Who: 20 Secrets from 20 Years if he writes such themes into the show consciously, the Welshman replied: "I don't even know if it's conscious. That's life, and I think it's the only way to write."
Davies, who also wrote acclaimed TV dramas Queer As Folk and It's A Sin, added that he felt it was harder to write using "a narrow window" of references.
"Why limit yourself? Why breathe in the exhaust fumes? Why be toxic? Come over here where the life and light and air and sound is."
Sethu, who made her debut last week as Gatwa's character's new companion, Belinda Chandra, also recently addressed claims around the show's perceived "wokeness", suggesting that meant it was on the right track.
"There's been a couple of 'Doctor Woke' [comments] or whatever," she told the Radio Times. "But I just think we're doing the right thing if we're getting comments like that."
She continued: "Woke just means inclusive, progressive, and that you care about people. And, as far as I know, the core of Doctor Who is kindness, love and doing the right thing."