Seriously, it's like RTD only makes enough episodes to tell the story that he wants to tell and then he thinks of a new story. That kind of crazy and wacky thinking doesn't fly in the States, where every story must be told until half the audience is good and sick of it.
Clearly, I'm having premature abandonment issues about RTD leaving Who. Also, this DW S4 spoilery picture is now my desktop (SPOILERS! Casting spoilers for the last three episodes of S4 of Doctor Who).