I think home user needs, or perceived needs has driven the market. Who remembers the MC2 which was considered bespoke in its day. Then came the Vario and the Mignon, then slowly but surely things developed. Everyone had grinders with dosers on. I bought a Versalab that I hated, then went back to Compak K series (both) then the E series (I think it was called). Things like Ceado E37s and E92s. Things really changed with the coming of the Niche Zero. It absolutely turned the market upside down! Premium Titan grinders came into play and have developed nicely.
So, for me to answer the original point. The introduction of the Zero and then the trend to do burr swaps. bearing in mind, 15 years ago the way into coffee was through a used Gaggia Classic and MC2, things have really come along way in a relatively short time. To make a further point, 20 years ago there were very few machines/grinders available and until Bellabarista came along, even fewer places to buy them!