But, according to the audio commentary for the episode "Selma's Choice," there is a perfectly rational explanation for Marge Simpson's iconic look. Apparently, all that hair was originally meant to conceal a pair of rabbit ears, and for all of you needy bastards who insist on fancy stuff like context: it actually turns out that this was all part of M. Night Groening's plan to reveal in the final episode of the series that Marge Simpson isn't human at all but, in fact, an anthropomorphic rabbit. (The funniest thing about that is Groening thinking that The Simpsons would actually end one day. Bless his heart.)
The whole idea actually goes back to Matt Groening's Life in Hell, a comic strip featuring a bunch of anthropomorphic rabbits and two gay guys wearing fez hats, because randomness equals comedy.
CUSTARD DILDO! See? Hilarious.
All right, all right; I actually do like Life in Hell and wish it had its own TV series, but where I merely wished, Groening acted by trying to sneak a character from the comic into The Simpsons. That's right: Marge wasn't supposed to be just a random cartoon rabbit. She was meant to be a character straight out of Life in Hell. But then he had time to think about it and decided that the idea was just too silly for a cartoon that, while admittedly out there at times, does generally strive for semi-realistic humor. He still gave Marge rabbit ears in The Simpsons Arcade Game, because, as mentioned before, randomness equals ORANGE PORCUPINE MITTENS!