The only reason Stern currently has a jump start in game design improvements at all is that coding is no longer a bottleneck.
That is an advantage of technology.
Many times BLY/WMS maxed out the EPROMs memory capacity.
You can ask any primary code designer such as Dwight Sullivan, Lyman Sheats, Jr., or Keith Johnson today and they will all say the same thing.
Even in the early 2000s this was a problem with games such as TSPP, and they really squeezed as much as they could into the game.
RoadShow is an excellent example from the 1990s.
There were more features planned, tested, and programmed, but they could not be implemented properly and had to be cut for the final game code.
I know this because I own the P-2 EPROMs from a sample game that was converted from a prototype.
I could see the differences.
There was almost as much in the game as the modes from TH.
I am still looking for the chips in my inventory, so they can be extracted.
I have yet to see anything in a Stern game that is revolutionary regarding design since 2001.
Every single device used in pinball design has been recycled since 1932 in one variation or another.
They are not "technologically advanced" because Stern's policy direction starting from the beginning was to make mechanisms "simpler" therefore making them easier to manufacturer and maintenance.
I am not dismissing any game as "fun", as a good design is a tested past design that worked.
Stern was not going to go out on a limb in the past 5 years as things moved forward.
Hell, they recycled their own parts for games, and openly admitted this repeated to simplify game design for manufacturing costs.
Not that this was passed onto the consumer/operator in any shape or form.
The couch lock for example in TSPP, is a variation of BK2K or even the original BK.
The three bank target assembly for SM has been used at least a dozen times, even before AFM.
The magna-slings on GB is TAF "Feel the Power" repeated with one less magnet.
People that toute Stern games as "overwhelmingly original" are new enthusiasts that have not had the opportunity to study pinball game history.
I applaud all game designs, but it really takes a good designer to come up with some new at this point.
I have no doubts it will eventually happen, maybe Stern SW, but not Aerosmith.
It just has not occurred yet with Stern.
BM66 is not a glowing example, it is retro retheme.
JJP actually took several steps forward in their games, however, especially with DI (using features in WMS 'Wizard Blocks' with Lawlor but never produced) and even Woz with the LCD interaction.
They should take some points from JJP, even if just for implementation of creativity.
Reliability of comparing BLY/WMS to Stern games is questionable. SPIKE has potential but continues to have teething problems on routes. WhiteStar and SAM improved with voltages, but still suffered from problems such as lack of fuse protection to protect against short circuits and overloads. IDC connectors also still burned. Capcom and AGC did a better job in those areas. Updating code capability on Stern machines is superior, especially now.