Fully agreed. The observation that SQL still works as well as it does today as it did in the 70s suggests that it's a good and valueable abstraction.
Are you saying SQL survived only because people have used it for so long and therefore its sustained use isn't an indicator of value?
OP said that it's probably good because it has lasted so long. I would agree.
Or... It sucks as badly now as it did back then.
It's easy sit in an armchair and point out all the warts on specific tech, but if you were to build a better solution to broad technology segments like this, and magically get adoption, you'd find that you only understood 5% of the application space, and your better version is subject to whole swaths of criticism that you didn't anticipate. Better to find one small/simple thing you can do well and build from there.