I always thought perhaps they just didn't give enough milk. That's only part of it...
Anne Saxelby, owner of a fantastic cheese-shop here in NYC, sends an e-newsletter always stuffed with tasty nuggets of information, and this morning's gave the real low-down on why we don't eat pig's cheese. It's because they're slop-eaters.
"The main reason that farmers of yore didn't make pig cheese stems from the simple fact that pigs, like us, are omnivores. Sure they eat slop and garbage of the vegetable variety, but given the chance, they'll tear into a chunk of meat faster that you can say "That's All Folks!" alla Porky. All of our other beloved milkers are herbivores, ruminants to be exact, meaning that they feed off of grass and transmit all that photosynthesized sunshine-y goodness right into their milk, creating an indelible flavor of fresh green pasture. It could be be argued (and I've never tried it so I don't know, but I have my suspicions) that cheese made from the milk of slop eaters wouldn't be so tasty."
She goes on to acknowledge the less-than-voluptuous size of the average pig's teats as another discouraging roadblock to milking a pig, in addition to their "somewhat nasty" dispositions.
Now that's making more sense. Still, I thought there must be someone out there making pig cheese just to say they tried, but not much came up in my research. I don't think I'll be the one to try it.