Buying used vs new speakers from a technology perspective

A lot of folks like older drivers in fact very old drivers can be quite expensive on the 2ndhand market. Some materials have improved but some older materials Alnico magnets are one example are considered by many to be better. So no don't be afraid of older speaker the answer as always is better is better not necessarily newer or older.

I think there's certainly some improvements in speaker design associated with electronics, material science and modeling/simulation tools that has resulted in improved performance.

Plus one. 

I think there's certainly some improvements in speaker design associated with electronics, material science and modeling/simulation tools that has resulted in improved performance.

When it comes to comparing 10-15 year old speakers to new speakers then there's certainly opportunities for time to degrade materials beyond regular wear and tear from usage.

Really depends, but paying 50% for a used speaker even 2 years old seems too much to me, let alone 14 years old.

In terms of parts, electrolytic caps wear but are cheap to replace.  In the 21st century finding top end drivers with amazing extension and smoothness is straight forward, and simulation tools make really poor crossovers like old Genesis/Infinity speakers inexcusable today.  Thinking of a couple of modern brands here ...  🤣

The vast majority of traditional box speaker components are decades old. Woofers are usually paper or some type of composite and tweeters are often silk or aluminum dome. In recent years, diamond and beryllium tweeters have come in the scene, as well as ceramic-come woofers, but there is no consensus that these modern materials sound better than the paper woofers or silk tweeter.  Truth be told, it seems that the older materials are often preferred from a sonic perspective. I believe the $600k Wilson speaker uses a silk-dome tweeter. Speaker materials are but one part of speaker design, and from what I can see, a relatively small part, assuming quality drivers are used.  So the short answer to your question is - yes there are some new materials being employed and no, there is nothing being made that audiophiles can’t live without. 

My Quad 57's are still in the top category of speaker sound despite being designed back in the Eisenhower Administration!

No!