There's a fallacy in saying that newer stuff is flimsier than older stuff: you know that all your working older stuff still works, but you don't know that all your working newer stuff won't still work just as long as the older stuff. All you can do is conjecture.
My personal conjecture is that there is no such correlation, but that any correlation is a result of a more global economy resulting in cheaper stuff being more widely available. In other words, I tend to think that it isn't that newer stuff is flimsier, but that flimsier stuff is more available. Buy the right stuff and it'll probably last just as long as your old keyboard you've been using forever.
There's also another fallacy at play: just because something has been working for 3 decades doesn't mean it will continue to work this coming week. Eventually, a problem will occur, and there's no real way to know when that will be unless you've been noticing a gradual deterioration of some kind, or there is a definite limit to life (e.g. flash memory), and even then, a different problem could occur before then.