More choice to the player would be a move in the right direction. The operator and manufacturer could then analyse the stats and see what the popular choices are. Another area for improvement and which has been covered in other posts is in keeping the player informed.
I keep looking at the cheap apron area of a modern day pinball and always think to myself what a waste of valuable real estate. With todays technology and as little as $50 at manufacturing stage, the apron is an ideal area to keep players informed. I could cast my eyes anywhere on the playfield during play and very easily see information in the apron.