We should be lucky that Stern are around, who knows what would of happened if they dropped away 12 years ago like the others - the industry would be totally different to what we have now.
Stern, SkitBpinball and sure JJP all use illustrator, corel, photoshop products as it allows you to do so much - it comes down to the artist and the attention to detail to make it look professional or rushed as well as licenses expect certain images on a game. Non license is risky so not used as much as the manufacturing industry in the US is doing it tough so they are cautious - is what it is. Some people love what is done and some don't and then the next theme comes out and it is opposite to the same people.
Back on Track - AVENGERS - rumour is not long to go.