The long-running BBC tea-time-television science fiction series Doctor Who is not without its problems, some of which I have considered before.
However, there is a simple solution which would radically realign the show, eliminate problematic biases and introduce exciting new storytelling possibilities, whilst squarely hitting the family demographic and exploring topical themes from a new angle. It is this:
I propose that the Doctor fixes the broken chameleon circuit which is designed to disguise the TARDIS time-vehicle as a doored object consistent with whatever surroundings it appears in: a passive form of camouflage. But wait! Not to apply to the TARDIS, which will remain the much-beloved police telephone box on the outside. But to apply exclusively to the crew.
In each excursion, the crew will pass through a chameleon convertor and turn into forms suitable for whatever environment awaits beyond the TARDIS door. More than a Mr-Benn-like makeover, this could fundamentally transform them into any required non-human shape: aliens of almost any biological kind and scale; mechanical or artificial life; or nonhuman animals from Earth's present/future/history, and beyond; or historically-plausible humans of all kinds.
This can all be achieved through computer-generated imagery, motion capture if appropriate, or in the last example case by truly diverse casting drawing on global talent. The consistency-of-character challenges should appeal to actors, writers and designers alike. Voice, badging colours, mannerisms and so forth will be used to distinguish the Doctor and companions.
The wonders this will open up!
The Doctor and companions will be able to appear throughout an alien society's spectrum, and interact with beings vastly different from humans, in exciting new ways and modes of thought. Explore Earth's history without white saviour establishment elitism, drawing on world cultures for stories and themes. Become marine animals on a coral reef (not everything has to be about a mysterious evil supervillain or struggle for the fate of the universe). The casting of the Doctor becomes less of an issue, and could vary throughout a season. The relations between companions and Doctor will be profoundly impacted by walking in another's shoes/animating in another's appendage coverings/experiencing society from a different circumstance.
Once the limitations of (Anglocentric, speciesist, fan-fic sexualised, anti-society, ego-driven) humanform acting are broken through, Doctor Who will finally be liberated to tell the stories our modern audiences need and deserve, with undoubtedly more appeal to global markets through new writers, stories, characters, actors and settings from around the world, and the wide popularity of the best nature programmes.