I know social media goes nuts about gender/race/etc of characters but as long as the actor/actress is right for the role I don't care if they are male, female, 20, 70, white, black, etc...
Although I would add that the showrunner is more important. Much as I could point flaws in Russell T Davies or Steven Moffat's writing (or things not to my own taste), they know how to write engaging characters and plots. Chris Chibnall has been responsible for some of the worst written TV I've seen in the last decade, and some of it won awards and praise too.
ie Broadchurch:
"You need to do your job properly."
"I can't, I'm too emotional!"
"That's OK. You are a woman after all."
Fuck off Chibnall. A hack who politicked his way into a job and then proved completely inept at even the basics. He wont be missed.