That was one of the points of this article—people see their themed lines, or their Friends line, and say "why can't it just be like when I was a kid?"—when what Lego said was "why can't we do both, and more?"
It's more likely the reality is the more specialized blocks come and go, and you only remember the more useful ones that survive the generations. There were junk pieces back then too.
It's kinda like saying "all music nowadays is trash, not like the old days". Sturgeon's law applies: 90% of everything is trash, and you only remember the best parts of the past.
When I was a child, the sets I received usually had some sort of theme, even if it wasn't a branded theme. Pirates, space, race cars, whatever. Also, as other articles have pointed out, the majority of the specialized-looking pieces in modern, branded models, are actually creative re-uses of pre-existing pieces. Re-contextualization.
One thing I remember distinctly is that my sets always came with two sets of instructions - one would build the model featured on the box, the other would use a subset of the same parts to build something related but different. Personally, I would usually build the intended model, play with it a bit, then disassemble it for the alternate model. Eventually that would get disassembled as well, added to the big box of unsorted Lego, and would be fodder for modeling some other random idea.
That said, I think I did more experimentation with the Technic line of Lego, which is more like a plastic erector set, than I did with the regular bricks. At least, I remember more of the experimentation with those, probably because it was at a later point in my childhood.
But then roughly once a year I would break down everything I'd built and sort every piece. Then I'd rebuild all the original models.
Funnily I have trouble swallowing medication, but I once put a flat 1x4 piece in my mouth for storage, but accidentally swallowed it. After that I'd always be bummed out when building my fire truck because it would be missing a piece. Back then in the 80's you couldn't get replacement pieces (at least where I lived).
But you could still make your bat mobile engine something else, if you let your imagination run wild during a building process.
Also, I've noticed that my kids (<8yo) both get new Lego, build following the instructions, then within minutes they will be moving pieces around to better suit their style. Or completely destroying it and making something they want to build instead.
Your opinion is common, but it reflects a waning creativity of a person growing older, not a major change in LEGO