I share your frustration with this and IMO it's a company wide problem. Maybe even an industry wide problem went it comes to the creative staff, namely the artists. I've been posting for a while now how Marvel doesn't seem to have as solid a roster as they've had in years past. Maybe it's salary, or workload...I honestly don't know. I think part of the problem may have to do with the expansion of titles when they got the Star Wars rights again. In the old days, there was only one title per month when they had the rights. Now they have 7 or 8 Star Wars titles. In fact, the whole line is bloated IMO.
But I really don't know why they can't have a more reliable method of assigning artists to titles. The fact that we've had switches this soon in the relaunch isn't good IMO. I don't know why Pichelli is already working on something else when promos played up the fact that she was on the title at least through issue 3 or 4. Even that is questionable. It used to be they would have the artist committed to six issues so that for the TPB, the art would be consistent.