I watch it mainly for the concepts and the occasionally masterpiece story. I had been looking forward to Matt Smith's second series but it just irritated me. Only The Doctor's Wife was the only decent episode. It's a shame because Steven Moffat has done amazing work with the re-imagining of Sherlock Holmes. Although I like Moffat, I find the more conceptually sci fi episodes more interesting. So if you look at the ones where they're usually on some sort of space ship, like in 42 or Waters of Mars (although in Waters of Mars we explored a nice plot). For these ones I don't usually mind if they don't have an amazingly original story but if you take the recent Christmas special it was just a mess. Nothing really Sci Fi to entice me, other than some random portal and the brief appearance of Bill Bailey as some acid miner in awesome looking armour. I don't often rewatch episodes of Doctor Who, so perhaps this is a reflection of how I feel about them. Perhaps as I watch them I imagine something so much more awesome happening before the disappointing solutions.
I have a feeling that people believe that people acting like children's entertainers for five year olds will actually suffice. Maybe they're lazy? You can have an awesome story without swearing and nudity and extreme violence you know. It's funny because you'll always find some silly character talking about various holocausts which take place in the universe and yet it all boils down to being silly.