I'm sure there are treatments for trauma and for stress, as you say. But short of something as unlikely as a long and very sheltered or stress-free life, a treatment for the normal stresses and process of becoming more and more familiar with the available experiences would amount to a form of anti-life.
Surely the prospect of a perfectly childlike adult would be an unhealthy one. It's the accumulation of experience and of wisdom that makes for the standard nostalgia, for the fond memory of our relatively innocent and naive childhood.
I'm sure there are drugs and treatments to produce every conceivable mental transformation, but that doesn't mean all treatments should be taken. Life itself shouldn't be medicalized, nor should we think that enlightenment is necessarily compatible with happiness. But sure, if happiness is the goal, I expect there are treatments for jadedness too.