
!! this post is like 70% headcanon/"what makes sense to me", proceed with due caution !!
Minor 3.5 spoilers, but nothing that wasn't in the trailer/patch preview - here's a good thread on tumblr that covers some of the ins and outs of magical healing (the replies in the notes have some good stuff). Thread TL;DR: It shouldn't be a magical fix-all, and it's not in the lore, even if for convenience's sake RPers are sometimes best served by treating it this way (e.g.: in fighting tournaments).
Something else I'll contribute is that the lore book states in Basic Aetherology that older, sicker people have broadly "less" aether than younger, healthier people. I can only imagine this is either a result of, or results in, a reduced "flow" of aether around the body... and we know (from Hydaelyn, the very planet itself, failing to regenerate after the Calamity) that a slowed or disrupted flow of aether prevents healing. This seems to be the in-universe reason for why, like IRL, older people are slower (when magical healing is not involved) to recover from illness and injury than younger people.
I feel like you could incorporate this into the reason why a healing spell isn't insta-fixing your character's problems? His body won't absorb the aether, or the aether is pooling in the wrong places, etc etc - it's no reflection on the skill of the healer themself, his body just isn't cooperating. Maybe the healer could undertake a longer plot to try and "fix" the disrupted flow of aether in your character's body - but even then it's better than an insta-heal (because it's a longer plot), and there's still the chance of it failing.
Though honestly, I think any healer who gets upset OOC because you won't let them take over and end your plot insta-heal your injury is a bad healer. Failures should be treated like a gateway to greater challenges (therefore more RP), not like a personal slight against the character/player.
Post TL;DR: Magical healing shouldn't pose an obstacle to doing long-term injury plotlines.
Minor 3.5 spoilers, but nothing that wasn't in the trailer/patch preview - here's a good thread on tumblr that covers some of the ins and outs of magical healing (the replies in the notes have some good stuff). Thread TL;DR: It shouldn't be a magical fix-all, and it's not in the lore, even if for convenience's sake RPers are sometimes best served by treating it this way (e.g.: in fighting tournaments).
Something else I'll contribute is that the lore book states in Basic Aetherology that older, sicker people have broadly "less" aether than younger, healthier people. I can only imagine this is either a result of, or results in, a reduced "flow" of aether around the body... and we know (from Hydaelyn, the very planet itself, failing to regenerate after the Calamity) that a slowed or disrupted flow of aether prevents healing. This seems to be the in-universe reason for why, like IRL, older people are slower (when magical healing is not involved) to recover from illness and injury than younger people.
I feel like you could incorporate this into the reason why a healing spell isn't insta-fixing your character's problems? His body won't absorb the aether, or the aether is pooling in the wrong places, etc etc - it's no reflection on the skill of the healer themself, his body just isn't cooperating. Maybe the healer could undertake a longer plot to try and "fix" the disrupted flow of aether in your character's body - but even then it's better than an insta-heal (because it's a longer plot), and there's still the chance of it failing.
Though honestly, I think any healer who gets upset OOC because you won't let them take over and end your plot insta-heal your injury is a bad healer. Failures should be treated like a gateway to greater challenges (therefore more RP), not like a personal slight against the character/player.
Post TL;DR: Magical healing shouldn't pose an obstacle to doing long-term injury plotlines.