Steven Moffat, our beloved Who showrunner, has been quoted saying this in regard to the Doctor's beloved TARDIS: “I don’t care where the Doctor came from or why he travels around the universe. I just want him out of those TARDIS doors and having adventures. Us kids want Narnia, not the wardrobe.”
That's all well and good, but I think there are a fair few among us who might disagree. Like those of you who spent your childhood locked in your closet, hoping against hope that if you pressed the back wall hard enough it might give way to something magical. Maybe it never did, but the time you spent in that closet was still very special. Those are the parts of childhood that shape a person, the moments where magic has the potential to become reality.
The TARDIS is an iconic symbol in pop culture. It is probably more recognizable around the world than any piece of clothing the Doctor has ever worn, any logo the show ever assumed in the opening credits. Every Who fan loves her, claptrap that she can be at times; she is the ultimate call to adventure, more so than even those legendary words, “I am the Doctor.” The sound of the TARDIS in your backyard means that something perilous, unbelievable, and wonderful is about to take place.
The TARDIS has gone through nearly as many makeovers as our dear Doctor. She often changes to suit her current pilot, and we've seen interiors that go from sparse white to retro-future to the more organic theme that we now see today (and so many styles in between; one of my personal favorites was the Third Doctor's retractable James Bond bed in the console room). However, she always seems to match the Doctor perfectly. In this way, though it may seem a little silly, I always kind of think of the TARDIS as the Doctor's daemon, ala Philip Pullman's Golden Compass trilogy. She is, in every possible way, a reflection of his soul, a part of him. She's old and wise, a bit wobbly and beat up, a little flighty and perplexed, but the only thing you can count on in the whole wide universe.
In fact, one could argue that she is responsible for most of the adventures we witness on the show: how many little problems start up because the Doctor means to go one place and the TARDIS takes him somewhere else? Again, the old girl seems to understand the Time Lord better than he understands himself. No matter how often he claims he is going to take his companions somewhere nice and lacking in danger, she knows that's not really what he wants. Whenever a companion wants to go home, she always makes it a bit harder than it should be because she knows that the Doctor doesn't really want to give that person up. Sarah Jane doesn't end up in Croyden. It takes all sorts of missteps and entirely botched landings (though the Doctor always thinks he has made it there) before Tegan ever sees Heathrow Airport.
Even at the end of last season, Amy is capable of bringing the Doctor back from oblivion—after he has been essentially erased from history—not because she initially remembers him, but because she remembers the TARDIS. That beautiful brand-new-but-old blue box that he “borrowed” from his people.
I think it's a testament to how much character the TARDIS has that you nearly always see someone cosplay as the TARDIS at various sci-fi conventions. She is a rightful character and deserves all the respect and love she garners. In the end, it exemplifies the human imagination; who could have predicted that a 1960s English police box would go down in history as one of the greatest ships in all of science fiction?
So Steven Moffat may think that we want Narnia and not the wardrobe, and in a way he's right—an entire season spent on the TARDIS would not be all that much fun. But if we got to see a little bit more of this 'whole world inside a box,' I don't think anyone would complain. After all, I do want to know where the swimming pool ended up this time around.
Emily Asher-Perrin has told all her friends and family that if she ever hears that telltale sound of the TARDIS landing nearby, she is diving on board with no warning. The Doctor will have to give her a month-long tour before she sets foot on an alien planet. She promises to document all of her adventures on twitter when it happens.