I totally agree. The Eleventh Hour was so special for me because of that wonderful scene of Amelia getting her case together and sitting in the garden waiting. This cynical, sceptical old(ish) man, actually got a lump in his throat at the sight of a little child waiting for the Doctor to return. It was so powerful and she acted it so beautifully.
Unfortunately the legislation in the UK concerning child actors (schooling requirements, rest breaks etc) are quite onerous on the production team and would cause two major problems. (1) Having her as a companion would be significantly more expensive than an adult actor because of the support she would need and related to that (2) The amount of time it would take to film the show would increase (also significantly) and if there was lots of night shooting then this would become a real issue.
This is a real shame as I totally agree - she would be amazing
