4. Two-Parters
Heres my theory on the lack of two-parters in series 7. I think it has way more to do with catering to American commercial interests than with the requirements of a story. I say this as an American and it makes me sad. So many of the episodes of series 7 have felt rushed and incomplete. A couple of them (looking at you The Rings of Akhaten) felt badly in need of editing. American hour-long drama shows include around 22 minutes or so for commercials. To sell to the American market you are forced into this format. Two-parters are discouraged and while there is nothing wrong with standalone episodes, it would be nice to occasionally take the time to explore a story a little further. I think a lot of writers have struggled with the time constraints of modern Who and consequently characters are undeveloped and endings have felt tacked on. Some stories take a little longer to be told and that should be OK.