Yes, there are lots of users who ask for banner rotation scripts or how to implement google's adwords or similar to coppermine-driven pages. But take at the sites those people ask support for: 99% of them are irrelevant in terms of page rank, so the revenue gained by adwords or similar programs will be just pennies per year. People scare away visitors by adding ads to their sites that they can't even start to make a living on. What you need to make money is good content. That's something most users don't have. Most think that they can get away with running a fan site where they host pics showing celebrities that someone else has taken or paid for. They just steal those images, upload them to their site and rely on others fans coming to their sites and clicking through thousands of paparazzi shots.
If we added a feature like the one you propose, there would even be more morons who added adverts to their sites without realizing that they won't actually earn money from it, infesting the internet with even more crap. Site owners who actually have quality content and a relevant number of site visitors will be able to add adverts no matter if there is a pre-configured interface in coppermine or not.
There are more important features imo that should go into coppermine's core, simply because regular site owners who run coppermine won't be able to do the modifications by themselves.