Theory 1) Editorial forced this. I tend to fall back on this theory often, thanks to DC.
Theory 2) This is temporary. Carol will be back, and soon. Of course, I had this theory after Cap 25 and it's been 23 issues now...So I could be wrong on this one.
I just can't bring myself to accept a person writing the book from Ish 1 would do this. Yes there have been signs he's been bored of Carol...But, damn, he made me -like- Carol. I just can't see him doing this.