Moffat on Hurt Regeneration

In the latest issue of Doctor Who Magazine, Steven Moffat explained why John Hurt's regeneration did not include Christopher Eccleston

It was one thing to include [Eccleston] among all the other archive Doctors, as they flew in to save the day -- in fact, it would have been disgraceful to have left anyone out -- but placing him in that scene might have given the impression he’d actually turned up for filming, which would have been crossing the line.

Not taking part in the 50th was a difficult decision for Chris, taken after a lot of thought and with great courtesy, and not respecting his wishes would have been grossly unprofessional and disrespectful to a good man and a great Doctor. Number 9 may not have turned up for the celebrations, but there would have been no party without him.

Via