In my experience it’s the evolution of amplification that has driven speaker design. In the 60 and early 70s even 35 watts of solid state was considered high power. Horn midrange or 12 inch woofers were common because of their efficiencies. This led to broad cabinets that brought attention to themselves as the sound source and deep bass that by today’s standards would be called muffled or wooly. Cheaper watts and high current have freed speaker designers to experiment with cabinet designs, drivers and crossovers.
Sound quality of Newer versus Older speakers
From a sound quality perspective, is there anything that newer speakers are doing better than older speakers. For reference, I have a pair of Monitor Audio Silver 300s which are amazing me with their ability to balance detail retrieval with an ability to avoid harshness (with the right ancillaries). My subjective perception is that this type of balance between resolution and refinement was more difficult to find in speakers from 20-30 years ago.