There is a great ted lecture on this subject. I thought he did a good job at addressing the concerns. At least to the point of defending that research should continue to at least allow future generations to decide if they think it is acceptable.
http://www.ted.com/talks/aubrey_de_grey_says_we_can_avoid_aging.html
You didn't talk about any self-fulfilling negative correlations. A volvo doesn't prevent accidents, just makes the accidents less deadly, so it may actually be the more reckless drivers that take them so they can continue to be reckless (this effect may be much smaller though) or parents that choose a safe car for their reckless teen. Another example is when seatbelts were introduced, the owners of cars with them became more reckless because they thought they were safer, and actually ended up in more accidents (though the death rate of drivers remained about the same because the seatbelts do actually offer protection, not just self fulfilling).
Maybe someone can think of better examples. I can imagine that these are hard to perpetuate though, because the concept that something is safer is often based on scientific evidence with proper selection, or real world evidence with distorted selection, but with a negative correlation, the distorted selection would show the safety device makes people less safe. You would have to have a good advertising team to overcome both the scientific and real world examples of your safety device. Either that or it really does make you slightly safer but the negative correlation effect would have to be strong enough to overcome that. But in either of these cases it isn't self fulfilling, because the concept isn't caused by the results, but either by actual benefit or advertising.