I think MP was banking on people porting the heads. Or use a replacement head well ported. There own Magnum R/T, Edelbrock or EQ. Etc... to the heads available at the time.
I always figured it ,as a building block.There were not a lot of aftermarket options,in the 90's when this was introduced. I don't have an issue with big cams,as long as they are reliable. Heads being ported, was a given.