Wait, I can take this further.
The appeal of severance, at least as we've been shown it so far, is that subjects can have unpleasant experiences (childbirth, a tedious workday, a dental exam) already having happened, to skip directly to the "afterward" and have the unpleasant experience actually experienced by another, lesser version of yourself. Right?
Which is also how a lot of adults feel about children -- either their own retrospective child selves, or the children currently in their lives (whose lives must be structured to best serve their future adult selves). The purpose of childhood is to get unpleasant experiences over with so that the Future Adult Self (the self-that-matters) can have them already over with.
It's so telling that the boss at the door factory who interviews Dylan compares severance to circumcision -- a surgery commonly performed on infants, without medical necessity, based purely on the justification "They'll want/need it done as adults." Now, that's not necessarily true (the world is fully of happily uncircumcised adults), but even if if were, it would raise the inevitable question "Then why not wait until they want/need it as adults?" and the answer is "Because surgery is unpleasant and we assume adults don't want to go through it. The Future Adult Self (the self-that-matters) will want this surgery to already have happened, to have been experienced by the Lesser (childhood) Self."
And people even do this with learning skills!
"I wish my parents had made me learn to play piano as a kid."
Why can't you learn to play piano now? What's stopping you?
What you mean is "I wish I were already good at piano-playing, I wish the awkward, frustrating, beginner stages of learning piano-playing had already been gotten over with by my Lesser Self who exists to get unpleasant things out of the way for Me, the Self Who Matters."
