Well, lo and behold here's a recent interview with him that addresses some of those very questions.
"Question: How picky are you? Good comedies are hard to come by and you've been doing this for so long now. Are you very selective?
Aykroyd: Obviously I'm not too picky if I got into Caddyshack 2 and a few other clunkers out there. But you have to look at how these things come to you. An executive calls you up and says he has your script on the table and he'll produce it for you if you play this part n Caddyshack 2. So if you want to see your script made you have to make certain deals."
I never finished my thoughts on this post..
Aykroyd has always been a little different. Not just an actor, but an intellectual. I have a feeling if he hadn't gone into acting, he might actually be a little like Dr. Ray Stantz on Ghostbusters. Even now, he sponsors a paranormal/UFO nonprofit organization and website. Not only an intellectual, he's a producer, director, writer - one of those kind of Hollywood people not just content to put in their hours in front of the camera and retreat back to the trailer. Because of these ambitions, Aykroyd has to make compromises at times to get his projects out there and in production. Some of these compromises were, unfortunately, like Caddyshack 2. And probably the Ghostbuster cameo he made in Casper, though I'm not sure. I've always respected him as an actor and filmmaker, and I'm sorry that not enough of the established Hollywood elite believed that enough to give him the freedoms he needed for his art.