Look at eg. the 787, A350 or A220, eg. modern airliners those have much bigger screens and more modern glass cockpits.
The 320 neo is based on the 320 which is a plane from the late 80s. They want to keep them very similar so the type rating carries over.
Another part I think is also that only professionals fly airliners, and with a co-pilot. GA planes are often flown by people that may not have very many hours and only a PPL. If you look at for example the checklists given in eg. a TBM and compare it with Airbus checklists, the TBM checklists are much more comprehensive, they are more like full on FCOMS. I read somewhere that is because A320 pilots are full on professionals with defined flows, so checklists can be reduced to the absolute bare minimum.
Just some thoughts.