I have a friend, respected marine researcher. He is 50-something and he finally got permanent job, only problem is that he has to move across Europe and learn new language. He was very upset, when I told him I already quit 6 permanent jobs before I was 30.
I think it's retained because it is a good marketing term, and lets technology (where the jobs are) benefit from an association with "hard" areas like pure math and astrophysics (where much of the prestige is). But that's a bit of sleight of hand: we get kids excited about "STEM" with documentaries about marine biology and astronomy, but then oops, that's not where the jobs labeled STEM actually are.
1) STEM graduates learn how to think critically and mathematically, two skills that will serve them well in almost any business pursuit. For example Jack Welch, the famous CEO of GE, held a Ph.D. in chemical engineering. I don't know of evidence that STEM degrees hold people back, even working outside the sciences.
2) We don't know, in advance, who the next Einstein is going to be. Giving as many children as possible the chance to make great discoveries is just good odds.
The chances are that most STEM graduates will not even be a full professor, let alone the next Einstein. But that is largely true of any degree we can imagine. Most English majors will not be a successful novelist or critic. Most business graduates will not run a company. Most history graduates will not become a full professor. Etc.
There is a shortage of leadership positions in any field, and a full professor with research funding is a leadership position. I think the most important question is whether the absolute best STEM graduates achieve these positions; that's best for society overall. If the postdoc crisis keeps the most promising new researchers from pursuing new knowledge, that's bad.
But it's not a volume problem. For the volume of STEM grads, the question is whether they can achieve at least a middle-class career and lifestyle. That might be in the sciences, but it might not. That doesn't mean that STEM education is pointless.
Problem is, an opportunity to make discoveries is not a degree, it's a stable job as a researcher after the degree.
I'd take it a step further: The problem is that our economy does not allocate resources well, either to people who need the resources (e.g., people who can't get health care or obtain decent education for their kids), or to people who will provide good return on investment to the rest of society.
The 'free' market, the invisible god that so many worship as an arbiter of value, doesn't do a good job. (It's also not free in many senses.)
It's a tricky one. While I am certain that science moves society forward (though the rate is decreasing), I am not convinced the median scientist contributes in the positive direction.
If you choose marine biology, maybe not so much.