From a materials science perspective there are positive advances. And there are advances in design capacity through electronic modeling technologies that allow the by-passing of multiple trial and errors.
Often changes get slip-streamed unannounced into components -- for example improved printed circuit board material. Sometimes manufacturers, for example Wilson, will collect several 'small' improvement and bundle them into a 'new improved' version which also reflect the higher cost of new capacitors, PCBs, viscoelastics, cabinet materials etc. Sometimes different technoiogies and materials are employed in new ways such as the adoption of slotless motors in turntables or sapphire and ruby bearings in Kuzma tonearms.
Much of the audio business is driven by the churn of such changes. Some manufacturers continually need 'change' as a rationale for introducing new models in order to stay in market headlines. So that stuff is out there.
The value of such changes is relative. Sure you can hear step-wise differences, nay even 'improvements' from, for example, version 5 to version 5SE, but across time there are few great leaps in sonics -- true mirabile dictu moments. What does not change is how the ear works, how people perceive sound and differentiate real from reproduced. Some manufacturers have unlocked the secrets of how we perceive sound and some asymptotically approach that in tiny increments ... and some, while producing exciting or exotic sound, never seem to be in sync with the rules of human hearing.
Being raised in the contemporary audio environment of say the last twenty to twenty-five years there can be stunning, ear-opening experiences when first encountering technologies of the past -- dare I say vintage technologies, or modern products that follow the path of vintage design. While modern speaker designers are adept, one might argue that the days of products from the likes of Klipsch, Altec Lansing, JBL, and even Advent, Kloss and Acoustic Research were the golden era of speaker making. And done so without the materials and technologies of today.
I had that 'vintage enlightment' experience. After going through Bose, Magnepan, Thiele, Audio Physics and three generations of Wilson speakers, and hearing countless other brands and models at shows and gatherings, it only took a few moments listening to the JBL M9500 for modernity to wash away. It was a 'scales fell from my ears' moment. Like sitting in my favorite chair or wearing a comfortable pair of jeans it was just right -- what I heard simply approached natural sound moreso than I've experienced previously.
I'm not saying contemporary audio is in second place to the past -- the industry continues moving. I am saying that the latest and greatest has no lock on what it takes to appeal to the human ear.