There are all sorts of reasons for this, the chief of which is genteelism, the notion that some things are 'delicate' and appropriate, while others are not. In sturdy rural or plebeian houses, getting one's hands dirty was part of the preparation of food, and no one has ever pretended that preparing offal of any kind is not dirty (bloody) work. In the 'better' sort of home, once kitchen staff had disappeared, such tasks as making one's own sausages (handling intestines) or cooking tripe were infra dig.
The gradual disappearance of the true family butcher - the one who knew his animals, did his own slaughtering (frowned upon by Brussels) and used every bit of what he slaughtered - is another. There is, in offal, something offensively visceral to modern taste. We live in a world where appearance counts for more than it ever did: hence the dominance of the chicken alienated from its own structure and off-the-bone cuts of steak.
The preparation of such homely dishes as tripe or blood pudding requires work, time and much handling of 'indelicate' materials, and there is not much you can do with the 'presentation' of such dishes: they exist in the pots in which they are cooked, not on a vast circumference of plate on which chefs can trace pretty patterns.
In short, for many of us offal is poor man's fare and somewhat messy: to be shovelled into the mouth with fork or spoon, not fiddled with daintily. The more cerebral we have become, the more we think instead of enjoying. And the moment you start thinking that a tripe is belly lining, you become less likely to try it. The dark, the bloody, the internal, the hidden are objects of fear and prejudice.
It is no easy task to get over this but, having often in my youth been constrained to eat 'poor', I early developed a love for the triperies to be found in back streets in French or Belgian towns, for tripes madrilena or fiorentina, for dark, oniony concoctions, richly spiced and, when accompanied with good bread and coarse red wine, immensely filling, tasty and satisfying.
The essential thing about tripe, as Jane Grigson noted long ago with reference to the tripe and onions one used to eat in the North of England, is that 'it needs to be raised from its visceral connections with a more seasoned form of preparation'. She was right: without art, tripe - while very tasty - can be bland and slithery.
Here is how my Emilian cousin prepares her version of tripe, a dish she claims originates in nearby Modena. You will need: 2lb (900g) tripe, blanched; enough stock (veal, preferably, in which you have thrown a few left- over greens, some chopped root celery, and a small glass of white wine), to cover; a bouquet garni; an onion, a carrot, a clove of garlic, about 2lb (900g) tomatoes, peeled and deseeded (or the equivalent in tinned Italian tomatoes), coarse red wine, allspice or black pepper, oregano, a pinch of baking soda, balsamic vinegar; some coarsely chopped country bread, olive oil, more garlic and a generous amount of parmesan.
Cook the tripe in the stock for about an hour. Remove, cool and dry. To prepare a sauce, sautee the onion and carrot, both diced, and the garlic, chopped, in a little olive oil. When the onion is golden, add a little flour to thicken, then about a half-pint of red wine, and seasoning of allspice or coarse black pepper. Add the tomatoes and allow to simmer with a pinch of oregano. When the sauce is thickened, add baking soda, salt to taste and 1tbs of balsamic vinegar.
Take a large solid casserole, pour in the sauce, add the tripe cut into bite-sized pieces and simmer, covered, over a low heat for at least another hour until tender, watching to make sure it does not lose too much liquid. While this is happening, fry chunks of bread over a low heat in olive oil and garlic, until dark golden, tossing constantly to prevent blackening. Dry thoroughly.
About 20 minutes before serving, check the seasoning for sharpness, then coat the top of the mixture with fried bread, sprinkle generously with parmesan and put into a pre-heated oven for five to 10 minutes until cheese and bread have formed a proper crust. Serve piping hot on heated plates (cold tripe can be unpleasantly glutinous).
It is a wonderful dish and needs nothing more than a sharp salad to accompany it and a good cheese afterwards.