I've been saying the exact thing as the OP for years. Innovation feels dead.
Most notable changes through out the years:
You had hybrid cross over machines (granny and the gators and baby pac)
Added spinning targets (introducing dynamic instead of static game play)
Added magnets (introducing dynamic instead of static game play)
Added magna save
Added CRT ALA Pinball 2000 (didn't change game play)
Added LCD screens (didn't change game play)
Added wireless (and still can't figure out how to do a Firmware check and automatically update a pin? Yikes) (doesn't change game play)
The P3 allows more dynamic game play because of it being largely software based but even then it doesn't really trip my trigger as it still feels too static.
Why not introduce a ton of randomness by adding more older technology and create a more dynamic experience? Subways with diverters so you never know what kick out you'll have the ball come from? Add a motorized kick out? Add a motorized coil plate that can change ever so slightly and launch balls out of a kick out differently due to English on the ball? I'm just spit balling but any deviation from the static game play would be welcomed with open arms by me.
And maybe, just maybe people aren't really wanting any real change and are happy with basically having new machines that are either a fan layout or stop and go. I feel like everything these days is basically the same machines with just different artwork and different toy.
I know the more they add the less money they make and potentially the more problems that can occur. The last thing OPs need is problems in the field.
If I was Gary Stern I'd run a contest and if your idea is selected then the first pin that uses your technology would be shipped to you for free as a thank you. Allowing community input would generate so much enthusiasm.