Thanks to all for your responses. I'll defer to your judgement.
No argument if we are looking for who (whom?) to blame. But, as the linkedin hack demonstrated, users are not particularly diligent in devising strong, esoteric passwords (among the top 30 passwords: link  1234  work god job from mashable dot com slash 2012 slash 0608 slash linkedin-stolen-passwords-list)
Okay, why would it attract attention? Some feedback mechanism the 'bot sends back?
Finally, I find I am not alone in finding capchas (or would that be capchi?) particularly annoying. See www dot socialreflections dot com slash unreadable-captchas-can-destroy-your-business
Again, I will defer to your comments. And thank you for your feedback.