I think the small touches in Maiden are as much a result of a new designer with new ideas as it is a matter of development time. Even the best designers fall into ruts over decades of refining their designs and it takes a new perspective to shake things up.
If you listen to the most recent Expo Q&A with Steve Ritchie about half the questions are along the lines of "would Stern ever consider adding variety to (playfield dimensions/toys/flipper configuration/etc)" and Steve basically saying, "look, we've refined the perfect pinball to within an inch of its life and that's how things are." Sometimes you need new blood to shake things up, even if the new blood doesn't have the clout to make them include a subway the first time out...