Earnest Cavalli said:
On the other hand, if these 'bots suddenly develop a taste for chemicals found in other, non-damaged parts of the body, they could do irreparable harm to their hosts.
This was my first thought as well. I'm also inclined to ask, what happens when they have no more "holes" to repair? And surely identifying problems (and teaching them to microspiders?) to 100% certainty isn't that easy. If they start patching up something they shouldn't, we're fucked.
Another question. Just how would our own bodies feel about hosting these things? The immune system doesn't take kindly to intruders, there is quite a few diseases out there that happen because the body simply thinks it's sick, or under attack, even if it's realistically perfectly fine.
Oh and to mimic what others are already asking (and I've myself pointed out in multiple Escapist News posts so far), where does the original article mention, allude to or has anything to do with spiders?