I believe it's a combination of factors.
Many of todays trad. archers have chosen to learn an aiming techinque that is considered to be more trad. and is actually harder to master, especially at longer distances.
Before there was 3D, there were Field Rounds, which had shot distances between 5 and 90yrds. and bowhunters back than had different standards and beliefs.
With todays average accuracy levels and what's considered ethical shot distances, 3D's are set up at an average distance of about 20yrds.
I believe their is alot of room to raise the bar...at least in regards to the Trad Class in 3D target archery competion, although I would still prefer that most 3D competions still maintain what would be considered an ethical shot distance and also create a specific class for trad target archers and allow them to shoot at far greater distances.
Ray