I don't get the big deal out of people wanting a prosthetic arm. Just be happy with the stump! Artificial arms look fake and usually aren't functional anyway.I sometimes don't get the big deal out of people wanting a penis, vagina, or a set of boobs.
What's wrong with just being a tomboy or effeminate male?
I'd find that much more attractive than an artifically designed member through surgery or hormones. Hell, I think fake boobs on a woman is kinda nuts.
I know that's an exaggerated metaphor but when you're dealing with people with body dysphoria, a clinical condition which can cause severe anxiety and depression, it's about your brain struggling with your body not matching the brain's expectation, much like phantom limb syndrome (or supernumerary phantom limb, where you feel like you have limbs you never did). It's not just 'wanting' a penis, vagina or boobs any more than phantom limb is about wanting the limb. The body and brain not being on the same page causes very serious damage.