When I am buying an oven, I look over the "self-cleaning" ovens. Why? It really isn't that much trouble to clean an oven (though my preference is to avoid the harsher chemicals which make it the easiest to do). Self-cleaning ovens do it by allowing very high (higher than most cooking is done at) temperatures to burn away drips and spills and leave only ash and easily cleaned residue. In order to do this, it is necessary that the oven walls be durable against both extreme heat and changes in temperature. It is also necessary to have good insulation around the oven so that the surrounding cabinetry does not catch fire or otherwise be damaged.
So, I don't care that strongly about an oven being able to self-clean. But the characteristics of a self-cleaning oven -- the insulation and solidity of the oven walls -- provide energy saving side effects, and a more uniform internal heat, that I DO want.
I am not a personal fan of cosmetics, preferring the unmodified beauty that exists in almost all people. But, since cosmetics are often applied in the same areas that also need protection from the sun, they can be modified to provide the Sun Protection Factor (SPF) that is useful to prevent aging, and damage, of the skin. Note that, in this case, the side effect is deliberate -- as normal cosmetics have rather low sun blocking capabilities.
Back in 2017, Neil deGrasse Tyson, for whom I have great respect as a scientist and as an advocate of science, decided to put in his oar concerning the value and/or potential problems of Genetically Modified Organisms (GMOs). His bottom line was simple -- we've been modifying the genetics of plants and animals for thousands of years -- there is no reason to be afraid of them now. The larger science associations agree with him -- American Association for the Advancement of Science as well as the National Academy of Sciences and the European Commission,
While I have disagreements about modern GMO creations being in the same category as those in the older traditions of hybridization and selective breeding and other "natural" methods -- I will not claim to have the scientific knowledge or backing to argue against the general safety of GMOs. Note, I still say "general" -- I still think that proper testing should be done against all foods, medications, and other items that will come into either internal, or external, contact with our bodies.
But, the investigation of Neil deGrasse Tyson stops too soon. To the best of my knowledge, he never went further into the "why" of GMOs and the potential dangers posed by that.
There are many reasons why a zygote may be genetically modified. Perhaps the manipulator wants to make the food tastier, or more resistant to grasshoppers, or larger, or have a greater percentage of protein produced. All good reasons (though some other qualities may degrade when one quality is improved). But many food crops are presently being modified primarily for the purpose of being able to better survive applications of herbicides and pesticides. In that way, an herbicide can be applied (perhaps rather heavily) to a food crop and it will survive while the "weeds" (undesired thriving plants) cannot.
So, on a first order, perhaps the GMO crops pose no danger to people eating them. But, on a second order, the modifications are often done to allow large amounts of pesticides and herbicides to be used -- which ARE, by definition, harmful to living organisms. In particular, glyphosate-based pesticides, considered to have quite bad effects on people, are banned in many parts of the world. Glyphosates have been found in (relatively) large amounts in human and other tissues.
I am sure that you can think of other examples where one needs to go beyond the "what" to the "why". Or go beyond the "what" to the "how". We often think of side-effects as not predicted -- but sometimes the side-effects are the primary long-term effects of a process. This can apply to physical products, software, business, or social interactions.
