I think the comedy arose from it being very hard to portray evil as arch theatrically without it being a bit comedic. A good Macbeth understates the role a little, despite the complete corruption of the character. I wonder if the Trek team of Next Gen were kind of learning as they went and there was possibly no benchmark for the Ferengi as I think they weren't TOS canon. Also, in a capitalist nation before the fall of "The Wall," the safest prie time critique of capital was spoof, perhaps.