Quoted from o-din:
Business was good and they were really churning them out so they could load them up with features and still make money.
Also they didn't have to cater to the "My dream theme was a band or movie from 40 years ago" crowd because there was no pinside, so they had to be creative with theme or use mostly current licenses with a few exceptions.
The designers of these games were also fairly young and full of youthful enthusiasm and creativity.
That was also during a time where there were arcades, bowling alleys, and restaurants full of pinball machines and lots and lots of people loved pinball. Now you have a very small group of people that like pinball and there are no pinball machines on location in most places amd the small percentage of people who do like pinball are mostly older people that enjoyed it back in the 70's.
Those themes are marketed toward the age group that is buying them. I dont know why that is so damn hard for some people to understand. Us old phuks are the ones that have the expendable cash and the desire to buy the majority of these games, and besides that every theme is not directed toward older people either.
Also Pinside is hardly to blame for the themes that are being made, these themes are what the majority of us pinheads want!