Don't agree. Some players have the vision and are facilitators, others are not. You will waste a good running outside back trying to make them into something they are not naturally.
To continue your statement, Julian Savea is a huge running threat, he requires defenders' attention. If Savea can develop his passing and supporting game, he could be anything. A second touch from him in a movement would be a real threat, much more a threat than a one out run.
Why not make Savea a 10?
Sure, you may succeed, but then again, you may not. If you succeed you may develop a good running 5/8, but he will never be a natural facilitator, and his natural running game will be curtailed somewhat. If you fail, you may have ruined a great outside back (or 12 or 13, whatever). Either way, you've lost a key outside back in the meantime.
If a Super XV wants to go down that road, good luck to them. But at test level, no way.
Now to the insanity of the previous situation...
What's more, why not do it in a key test series that only occurs every 12 years? That's before the following information:
1. He was trialled there a few years ago for a few games on an EOYT, and the same coach was quoted as saying "[he] is not a 10".
2. He played at 10 during the Super XV this year, and was poor - in fact, he was out pointed by Cooper, who had two charge downs leading to tries in the same game!
3. He is disliked by most of the players on the team (Wallabies or Rebels, take your pick), is known to have attitude problems, and frequently breaks team protocol.
4. You know he views himself as a "star" player, who generally looks to his own opportunities first.
You think this is just the player you want to develop in a key position in the team (in which he was little to no experience) in which he has to develop key combinations with other team members in a short period of time?
I hold my head in my hands at the amount of people on here who supported the JOC (James O'Connor) at 10 call.