I have been avoiding writing this because it will inevitably sound like the cranky rantings of a disgruntled fan boy. But having just finished Season 3 episode Seven of the Dr. Who reboot, I have to get something off my chest that's been bugging me for about a season and a half.
Let me pause before the onslaught to affirm that I do, in fact, enjoy the show - more than I expected to, truth be told. With that said, the constant recurrence of the Daleks and Cybermen have been bugging me, and it's getting in the way of my enjoyment of the rest of it.
For the uninitiated, a bit of history: in the Dr. Who mythology, the universe is almost constantly under dire threat by goofy looking mechanical things who, even though they move stiffly, possess no organized space navy that is ever revealed to the camera, and spend more time monologuing than Bond villains, are considered a credible threat to All Life As We Know It™. Chief among these are the Daleks, small mutant soft-shell crabs that move around in 2 meter tall pepper pots dotted with tennis balls and menace nearby organics with a plunger and egg beater, and Cybermen, zombie suits of armor implanted with a human brain and otherwise indestructible. Long time fans of the series know that these two enemy races have undergone much revision over the run of the show (the Daleks even have two entirely separate creation myths) but all of that came to a head when Doctor Number Eight sacrificed his planet and race in the Last Time War. Though this act would bring a new poignancy to his endless wanderings, the Doctor made this sacrifice to ensure the complete obliteration of the aforementioned bad guys.
Except they weren't actually obliterated. Like a long lost twin or jilted lover in a soap opera, Daleks and Cybermen have a nasty habit of coming back whenever the show needs ratings. Originally we were asked to believe that one Dalek fell through a crack in time (something else that keeps popping up conveniently when the writers have backed themselves into a corner; cracks in time are to Dr. Who as tachyon particles are to Star Trek: The Next Generation) and was experiencing a Borg-like separation anxiety, having been cut off from the Dalek Collective. Then we are told that a long lost Dalek Emperor, the God of the Daleks (I always thought they were created by a crippled scientist? On this, at least, both the competing origin myths agree, so who is the Emperor?) survived along with scores of thousands of his brethren. No sooner is this threat defeated than we are informed of a parallel dimension in which the Cybermen evolve, not as a tool of military might as before, but as a life support system for a powerful, eccentric trillionaire, and yet look enough like the Cybermen from our universe to spook the bejezus out of a human who had seen the head of one in a museum. Eliminate that threat only to have both the Daleks (this time with a Galifraian prison craft containing millions of their kind) AND the parallel-universe Cybermen converge on present-day London. Get THAT issue resolved, and the individualized Daleks of the Cult of Skarro do an "emergency temporal shift," all the better to attempt to claim the entire human race as slaves during the Great Depression. When the Doctor accidentally shows up to stop THAT plan, the sole surviving Cult of Skarro Dalek does another emergency temporal shift, despite the fact that the first one supposedly trashed all their power cells to the point that a command performance wasn't possible, hence the zany take-over-the-humans plan in the first place.
On the face of it, this isn't really all that different from tactics employed by a number of other sci-fi series and comic books. The frustrating thing is that it takes all the dramatic tension and symbolic importance of the Last Time War, crams it into a trash can, sets the trash can on fire, and then throws it out the window. The mythic point of sacrificing your family to save the world is well established; to conveniently ignore such an act in the name of fan service at best cheapens it, at worst invalidates an entire incarnation of the Doctor. It also shoots an unfortunately emo strain into the current Doctor's personality; if he has made truly the ultimate sacrifice, only to constantly face the enemy he thought he'd bested whenever a writer gets bored, then how could you possibly expect him to have any reaction but tragic melancholy?
The whole purpose of a reboot is to take a beloved icon and reinterpret it in a modern sensibility, to ensure that the meaning of the story remains relevant even as the context in which its told morphs into something beyond recognition. Why bother to establish the destruction of the old if you aren't willing to focus on the new?