However, it's honestly pretty ridiculous to pretend like marketing does not have an immense influence on the trajectory towards consumer desires or that it cannot lead to worse choices by many objective measures. See cigarettes, fast food, hell, even the stupid obsession with buying bank bustingly expensive diamonds for marriage proposals. There would definitely still be a market for all of the above (and personally I am against any regulations limiting the freedom of purchasing even cigarettes for legal adults) but it was marketing that turned it into a cultural norm, not organic consumer demand.
It also does not need to be something that starts off as a bad thing. Thinner devices are better up to a certain point, no argument there. However, it does start leading to usability and maintainability problems past a certain threshold. We have definitely reached and passed that threshold for many devices.
Customers don't exist in isolation, if you are locked in to the Apple ecosystem, you're stuck with their decision to ditch the headphone jack unless if you want to stick to phones before iPhone 7. If your family have been purchasing Samsung devices predominately, chances are you will just assume that it's best to just get one of the latest one because it's reassuring to get a familiar brand and surely the latest automatically means better, right? Feel free to strawman this as me claiming people are morons but for most normal people not preoccupied with tech, these assumptions are reasonable.
Also, pretending like blatantly unpopular decisions like removing the headphone jack and expandable storage are somehow in demand based purely on continued sales figures is stupidly reductive. Humans don't have perfect knowledge of the market and the leaders of that market will not only dominate airtime, they can afford to absorb bad PR if they deem that an unpopular decision will lead to better profits long term.