Pinball doesn’t have enough of a market to truly inspire “leaps and bounds” style innovation. R&D is expensive and takes quite a while to generate a return on investment. There just isn’t enough large growth sales potential to justify that risk in pinball. That is the reality. If sales of pinball machines were equal to those in the automobile industry or video game industries then you would see innovation.
However, re-using more of the existing design elements of the past in new and interesting ways could be interesting. But again someone has to take the risk with their money to do that.