I think having both the TARDIS and the Doctor as females might add a bit of commonsense wisdom to the team that the Doctor has somewhat lacked in the past.
The Doctor is the Doctor. They'll always be silly and reckless. :)]

Ha! You're probably right, that is part of the Doctor's core being... never looks at the TARDIS monitor before leaving the ship and finding out that they aren't where/when they think, and it's right in the middle of a disaster!