Even before the Clone Wars, Padawans accompanied their Masters on fairly dangerous missions. I don’t exactly remember the youngest age to be eligible to be selected as a Padawan, but I believe 13 was the oldest (with special exceptions made during the Clone Wars because of the lack of available Masters, so Ahsoka is actually quite old to be, er, ‘selected’). Based on the books depicting Obi-Wan as a Padawan, he was thrown into some fairly dangerous situations when he was barely a teen.
As you pointed out, the Doylian rationale is that these works need audience surrogates, and those surrogates are going to be children. From a Watsonian perspective, however, I can’t help but conclude that it is not unexpected for young Jedi from around 13 onwards to encounter life-threatening situations or various other traumatic experiences, even when there isn’t a war going on.
(I personally get the impression that the Council doesn’t like sending so many young Jedi off to war, but just like with everything else they feel their hands are tied. I see it as part of the general theme of the structural corruption of good intentions.)