Like others mentioned it just made sense to capitalize off of the Avengers success by following up with Marvel Studios most popular character, and I suppose it was also appropriate to start off the 2nd Phase of the MCU with the one that help make it possible. TFA was the 2nd least successful MCU movie, and it preceded the Avengers, it would have been a bit much for the general public to have another Captain America follow it. I'm pretty curious about the chronology as well, IM3 takes place 6 months after the Avengers, and I think T:TDW is 1 year after the Avengers, AoS concurrent to it. Unlike Thor there needs to be an explanation as why the biggest intelligence organization was absent and uninvolved when a terrorist organization had the country under siege and the President gets abducted and somehow Captain America is unavailable! Did the AoS show even address this, they sure incorporate Extremis into their storyline but I suppose side stepping that whole situation would be another of the shows shortcomings. Although TIH was originally scripted as a direct sequel to Ang's Hulk it was later decided that it wouldn't be and it irks me that people still think of it as connected. If Ang's Hulk never existed I bet TIH would have had more fruitful profits... Anyways I don't think it was ever the intention of Marvel Studios to stick to a steady pattern, apart from ending each Phase with an Avenger's movie. Patterns don't work when you have limited slots per phase and need to introduce new properties.