People wanted to be in the 11th squad most of all? SCARY SCARY, JAPAN. I assume it's because of the brotherhood and not for the fighty fighty. And to feed Yachiru konpeito. Adorable that Kubo worries about the popularity of a squad he hasn't written yet. I reminded of his concern for Hisagi's popularity before the character was developed. He doesn't seem to like audiences' imaginations running away with them before he has some say!
Oh, the songs cover tidbit that Syn refers to in her comment is from a tweet of Kubo's about Buricon 2. Nacchan's post about the tweet is here. "He said that he likes how at the end the flow of the songs are Kaien --> Rukia --> Ichigo."