I think you have missed the point. Please see my response to "lamontcg" in this thread for some rebuttal.
Note that it is not just Sale (though of course he is quite extremist in his views) who has pointed to the deleterious effects of our Technology, Social systems etc. which may lead to "Collapse" of our Civilization; you also have Nassim Taleb, Jacques Ellul, Michael Ruppert espousing similar arguments in different contexts.
All that you mention are "local effects" having their own unforeseen long-term negatives, due to self-limiting feedback loops, for example (without making any moral/judgemental/ethical calls);
>global poverty line has been on a steady decline over the last three decades
Debatable and for a certain definition of "poverty". Inequality has only been increasing and if i am unable to afford stuff even though i make more today then i did a few years ago, that is not "alleviation of poverty". Even if we accept your argument we now have the problem of increased middle class population leading to rampant consumerism and pressure on both social and natural resources.
>untold advances in the medical sciences
True but the other side is also adapting itself to work around our efforts eg; "Superbugs". We also don't know what the long-term effects of genetic engineering would be. There is also the problem that advanced medicine leads to longer lives and thus more pressure on social safety nets and healthcare.
>we are rapidly divorcing ourselves from our reliance on fossil fuels
Wishful thinking; we have a long way to go and given our propensity for short-term fixes we may very well run out of time.
>when there is an unprecedented level of awareness for basal human rights
Awareness does not necessarily lead to Usage/Implementation.
The above is not to say that "good old days" were "very good" and we should blindly roll back our scientific and technological use. On the contrary just like we have realized that Atomic warfare is unlike anything ever experienced by mankind and hence has to be prevented and dealt with in a whole different way than we have ever handled our "differences", so should our use of Science/Technology towards the betterment of our Societies, Other Species, Natural Resources and ultimately the whole Planet.