Originally Posted by Luckless
I'm assuming a big part of the age thing is that the actors appear to be at that age where they can prove to be reliable actors, while still clearly 'very young'.
Personally I have no issues with logical changes like that for a live action film that are based on general logistics. Changing ages and some time lines can be done very effectively while keeping the core of the story itself alive.
Well, you'd have a hard time getting the naked shower fights and two brutal hands-on murders by Ender past the MPAA if they used actual 7-10 year old actors.