@Silvaire1
The problem as I see it is that the GA industry in the US (which is the largest market in the world by a large margin) basically died in the mid 1980s and didn't slowly come back to life until the mid 1990s.
This was an era of massive technological and design advancement. GA benefitted in terms of avionics but there were very few advancements in GA airframes or engines from the "big three" US manufacturers from the mid 1970s onwards.
The attraction of Cirrus & Diamond is that they build GA aircraft using more modern technology and design.
I really enjoyed getting my PPL in a 4 year old 172 but it does feel a bit odd that it is not much different to the plane that my dad flew nearly 40 years ago.
I guess that I am a person who likes to see progress.