What Vid was referring to earlier with respect to certain companies giving artists a limited number of images and/or looks that they're allowed to use is what's called a Style Guide.
I'm a graphic artist by trade and often I do work for Disney, Dreamworks, and a few other big names with huge, huge properties. They all have them and they all supply them. These companies are extremely strict about the use of their imagery, IP, and copyrighted material. You either use it according to their rules, or not at all. It also helps them identify counterfeit products easier. That being said, they do allow some leeway for customization based on the product it's going on. They do allow certain liberties to be taken by the packaging or label artists, but they still must approve the final product before going into production.
There is a very, very good chance that these images Stern is using were either suggested by the contracted artists, the only ones with high enough resolution to be used in such a large area, or the only ones Stern is allowed to use according to the rights holders. There are plenty of artists out there that could've hand drawn something completely new just for the B66 pin. That much should be obvious. It also simply could've been a cost cutting measure. I'm certain getting new custom artwork for each of the characters would've cost well into the five figure range and most likely around the six figure range. Given the limited number of pins Stern is making overall of the B66, that cost wouldn't have been recouped very well. The added cost per unit would've taken out a huge chunk of their profit. And I'm sorry, but all businesses need to turn a decent profit to stay IN business. They're earning a lot of warm fuzzies for making the B66, but warm fuzzies don't put food on the worker's tables.
Those images shown so far indeed used the same source images seen elsewhere on the model kits or whatever they were. It is extremely easy in Photoshop to take even a finished "uneditable" image and modify it the way they obviously have for their playfield art. They probably had to do most of those modifications simply because of the playfield printing process and the way it processes colors and shading. I've had to do those things with artwork I've received from Disney many times and they're always ok with it.
While it is fantastic art, it would've been nice to see something game-specific, meaning it could've ONLY been used with the game because of a layout feature or something. Batman running around with a pinball over his head, like the bomb from the movie, tucked away in a corner or in the entry to a loop would be super easy to do...