Davison: Companions weren’t well-written until Rose
He told the Radio Times: “They were struggling for many years to find a better way of making the companions more rounded characters. And certainly, when it comes to the female companions, they never once thought that it was a good idea to put any kind of sexual tension, even in its most innocent form, between the Doctor and companion. I think it probably would have made it easier to write a better character.”
“I think the idea that there’s a kind of frisson in the TARDIS is fine and works actually rather well. I’m rather envious at the number of times that the Doctor gets to kiss girls now.
“They struggled for many years to write a good companion’s part and didn’t really ever manage it. In fact, I don’t think they’ve ever managed to do it until Rose, when the series came back, and that was really just writing a damn good part.”