I don’t think any decision to apply GM methods was driven by what was happening in society, per se. It was driven by advances in science and technology that made it possible to do genetic engineering. There were obvious targets to try in agriculture (herbicide tolerance and insect resistance), and particularly companies who had interests in these areas focused on it and made it work. Public-sector research continued also, with some successes (virus-resistant papaya).
In those early days, it was not realized that there would be major regulatory supervision associated with GE, nor that there would be a strong public backlash, as particularly occurred in the EU. It is possible that a different approach by the companies involved at that time could have reduced the strongly negative public response, but there were also NGOs who were always going to oppose it, so it is not clear how much difference this would have made.
From the scientists’ point of view, this was just an obvious extension of breeding and crop improvement methods that they were excited to utilize. Up until that point, breeding methods and changes in varieties (particularly of commodity crops like corn or soybeans) were not public issues. Crop varieties changed all the time as improved ones came along, and this had never been an issue that needed to be vetted by or even brought to the attention of consumers. The customers of the GE products were seen to be the farmers who buy seed, so the initial goals were to solve their problems. There was no “turning point” from the scientific point of view, other than the capability to do genetic engineering, because at the time it was not viewed as something that would be particularly controversial. I doubt that Edward Jenner anticipated that there would be antivaccine groups or that Alexander Fleming expected anyone to challenge the value of penicillin. These were scientific advances with obvious benefits to society (e.g., stopping smallpox and microbial infection), and I think that was the scientific environment in the early days of crop biotech (e.g., controlling weeds and insects that reduce crop yields).
After the discussions at Asilomar, where protocols were developed to do laboratory DNA manipulations in contained ways, the science side has continued pretty much unabated and has been widely implemented in medical practice (“red biotech”). On the food side (“green biotech”), the science has continued but the applications have been substantially stymied by the regulatory and market hurdles that have been imposed for commercialization. So the real social “turning point” was not when scientists decided to use the rDNA techniques in agriculture, but rather when society decided to be scared of them (promoted by the exaggerated fear-mongering of anti-GM groups like Greenpeace, the Union of Concerned Scientists, etc., particularly in the EU) and suddenly made them controversial.
To present an analogy that I often use, was there a social turning point that encouraged Steve Jobs and Steve Wozniak to create the first Apple computer? The basic technology was available, and they were making creative use of it. The open innovation and commercialization environment for that technology allowed an exponential increase in creativity and novel applications that brought us all the things that computers do for us today in a remarkably short time. In the case of crop biotech, that same initial, exponential increase in innovation and novelty with a new technology was abruptly truncated by the negative public response and the moratorium in the EU, followed by the requirement for regulatory approvals (and their differences in different countries), the anti-GE hype mythology and so on that continues to prevent beneficial applications of GE in food to be fully utilized today (c.f.: Golden Rice is still not saving lives and preventing blindness, due to these issues). (See this paper by Graff et al. that documents the abrupt halt in innovation coinciding with the EU moratorium.)
So, again, it was not a “turning point” for scientists themselves that led to the application of GE in agriculture; it was just the consequence of the advance of knowledge and technical capability that made it possible to do rather obvious things. Rather, the turning point was in the negative campaigns against crop GE that subsequently changed it into a scary and negative development, stymied its advance and continues to make it a source of controversy, rather than of solutions to the pressing problems we have in continuing to feed the world sustainably.
Imagine where we might be now if the initial exponential innovation potential of green biotech had been allowed to flourish as it did in electronics. Given the current prevailing social view of GE, that is probably quite scary to many people, but how many of those would give up their cell phones or computers? There have been negatives associated with computers and the internet also, but I think most would say that the benefits vastly outweigh the negatives. Similarly, there might be false starts or failures in the broader application of biotechnology in agriculture, but are we really better off in trying to feed the world using the biological equivalent of 1970s Apple II computer technology because society refuses to allow its further development? The lost opportunity costs of this social attitude have been enormous and continue to multiply even as global climate change shortens the time for breeders and agriculturalists to respond with adapted varieties. Let’s hope that there can be another social turning point enabling us to unleash biological creativity and innovation and get serious about tackling the issues of food production and security.