How far has speaker technology come?

Currently I am using my dad's old Wharfedale E-90s. From what I get from talking to him about it, they retailed for somewhere in the neighborhood of $2000 dollars back in the 80's when he bought them. I guess if you want to scale the price back then to todays money, taking into account inflation and what not, they are probably the equivalent of an $8000 pair of speakers in todays market, at least as far as dollar value is concerned. But anyways, does anyone have any idea or opinion as to what I improvements I should expect to hear if I were to buy a more "modern" speaker which retailed for about $8000 new? Could I expect the quality to be substantially better, seeing how these speakers are over 20yrs old? Can a dollar today buy more speaker "bang" for the buck, or has it stayed the same over the past 2 decades? Has the area truly advanced, or is it just running around in circles? Is the progression as obvious as digital technology? My dad is also looking to purchase a newer speaker for about $2000 used. For that amount of money, could he expect to find a speaker "better" than the E-90s? I've asked retailers in my area, but their opinions are inherently biased, so I want a "real" opinion. I do understand that the word "better" is subjective to interpretation, but I am sure there has to be some widely acceptable basis for evaluation. Clarity, imaging, detail, presentation.... all those good things.

Thanks in advance
Clarity, imaging, detail, presentation... in dynamic speakers, should be better with contemporary mid-level offerings. Drive units' materials have evolved, so have design and production processes, making once expensive models more reasonable.
Also cross-over components have improved. Last, computing power & design s/ware have improved and prices have gone down there too. Overall, many contemporary speaker manufacturers take phase, distortion, and transient/amplitude characteristics into account, and can model the speakers using test equipment that was once untouchable...
Not least, today's speakers are more efficient than many older models..

On the down side, the basic design principles have hardly evolved; as a product, many commercial speakers are still quite expensive especially if you want a true full-range
The biggest differences with modern dynamic speakers is the use of narrower front baffles and smaller speaker cones. A less wide baffle enhances imaging. The smaller cones are easier to control. However, moreso than with any other link in the chain, actual listening is the key to choosing any speakers, even vintage ones. Enjoy your search.
those wharfedales are infinitely musical and would indeed compare to speakers costing over $5000 today. the wharfedales of that era where sought after by folks with large music collections, who valued the timbre and weight of real music over imaging. this notion still works for me.