Have speakers really improved within the last 20 years??


Question:

  • If there is one measurement that would prove that speakers have indeed got better over the last 20 years, what would it be? 

I dont just want one example of a speaker from today that has a better measurement than another speaker from 20 years ago because that could just be a coincidence. I want to see IRREFUTABLE PROOF that most speakers today have a measured performance in at least one area that is better than most speakers 20 years ago.

When I look at a typical bookshelf speaker from 20 years ago versus one from today i see little difference. All i see is a wooden box, typically mdf with a pair of drivers in 'em. There would be a small crossover circuit inside and a bit of foam inside the box and that would be the end of the story. I would like to believe that speakers have gotten better but I see no reason to believe it. All I see is that speakers may have gotten brighter and brighter with time to dupe us into thinking we are hearing more detail. 

This challenge is open to any audiophile or speaker designer reading this.
kenjit
I have wondered about those people who seem to prefer vintage equipment over more recent offerings.  Receivers from 40 years ago, like Pioneer SX1280 and Marantz 2500, fetch prices of $2500, while I have seen JBL 100 speakers listed for $2,000 for the pair.  I assume that people pay those prices not just for investment value or sentimentality, but because they appreciate the build quality and the sound.  I wonder why they wouldn’t apply that money to more modern equipment if sound reproduction has improved over the decades.  
@kenjit 
  • If there is one measurement that would prove that speakers have indeed got better over the last 20 years, what would it be?

weight
@kenjit Yes, speakers have evolved.  Quite a bit.
But, have new speaker systems been developed?
Not so much, we still have
  • dynamic
  • electrostatic
  • magnetostatic
  • piezoelectric
speakers; but nothing revolutionary different from those have been developed.

But each category listed here has evolved.
I'm with speed-up.... Prove it isn't so - and to make it easy for you - use the measurement of speakers 20 years ago, including distortion components, versus , say a rather basic Revel M126be of today. He he... as your post, all in fun :)
@ptss  This is my challenge to you. You dont get to change the rules of the challenge. It is non negotiable. So you either admit defeat or you post evidence. What you are doing is trying to turn the tables on me because you are unable to solve my challenge. Your evasiveness does not impress me you are hereby dismissed from this discussion.