I have older speakers and newer from 1978 to 2017. The biggest improvement IME, has been the noticeably better audible performance from budget speakers. 40 years ago, there really were no bargains either in home, or car audio. Bargain speakers back then were very much Lo-Fi and often unlistenable for all but low volume background music at best. Some would blow the first time you floored the volume, or came with so much built-in, mechanical distortion, that they may as well been blown.
These days, even the $2-300 all-in-one shelf systems like that from RCA, Sony, Phillips etc., while not audiophile grade, are actually acceptable and certainly better than the boom-boxes of the past. Now, a couple hundred bucks will buy a couple hundred portable watts, and 8" 3-way separate speakers that at least show up to jam without blowing out and with plenty of somewhat clean bass.
Now I have a pair of powered JBL LSR305 I use at work. They're not even located well, yet they stop me in my tracks sometimes with the things that they do well. I paid $200 for them on sale a few years ago.
One major difference is the tech age's computer simulation and controlled manufacturing and the ability to design without a mountain of failed prototypes or a whole team of engineers. Computers really don't know how to design bad speakers on their own. It ends up now being pretty much up to the marketers on how much they allow the computers to give us for our money, with some differences really being how many exotic materials they include, or what level of cabinet finish we get.
As much as I have tried to take tech at their word, I still like displacement of large drivers. As soon as I hear, "they sound so much bigger than they are," I run the other way, because who says that, either doesn't listen as loudly as I do, is kind of new to all of this, or their wooman won't let them have big speakers so they don't want anyone else to have them either.