I developed a medial distal forearm neuromuscular twitching and discomfort the first week or two wearing a Sport band. Resolved each time I switched wrists. Eased the band one hole looser and the discomfort vanished. No recurrence for months. The band bunches a little on the ulnar volar wrist where the end of the strap inserts into the other half, putting slight pressure on the structures there (ulnar nerve, artery, muscle, tendon or some combination). Not carpal tunnel because not median nerve. No harm done. Love my Sport Apple Watch.
That's why we evolved to have sensory changes millennia ago - so we could adapt to the coming of the Apple Watch.
Seriously, we need to keep this in perspective. I have no doubt that pre-Internet watches caused similar pressure symptoms, but now that millions of us are paying attention to the same watch brand with free easy access to Internet forums like this, the few of us affected can report these experiences.
Quick Google turns up lots of similar reports in other watch brands, e.g.
http://forums.watchuseek.com/f2/pain-due-watch-494488-2.html