My answer to "why", I realized, is not JUST because I'm a raging control freak who needs to be personally responsible for everything I put on my body, either in termsof creation or collation, but also because I love the way it feels to sew.
That's right. Sewing feels good. It feels good in the same sensual, atavistic way that holding a just-bathed baby feels good, and it feels good in the same disembodied, intellectual way that writing a computer program feels good.
Replace "sewing" with "cooking" and I could've written those sentences (especially the part about being a raging control freak). This, of course, is further evidence backing my belief that there's very little difference between most connoisseurs - even casual enthusiasts - with interests in sensory hobbies. Food, art, fashion, music. It's all the same in the end: sensual, intellectual, and good-feeling.