I think it helps to stop thinking in terms of "meat replacement" or even "main dish." We're so used to meat being the main dish and vegetables to being mere side dishes, that when we go from meat-eating to vegetarian eating, we still think, "Okay, what do I replace the meat with?" We picture a plate with peas, mashed potatoes, and a giant blank spot. What goes in the blank spot. Veggie loaf? Meat eaters all cringe at the thought.
Instead, I may serve up several dishes that contribute equally to a meal: a thick bean soup, a hearty whole grain bread (I love my bread machine!), and a tossed salad with walnuts and some really good cheese.
I'm not vegetarian now, but I have been in the past. For me, it's not a matter of labels and rules, and deciding, "Now I'm a vegetarian, now I have to eat certain things." For me, it's simply that I find vegetarian foods more interesting, with a wider variety of flavors and textures. When you think about it, there are only a few kinds of meat that we can get at the grocery store, so meat every day gets boring. I'm also weird about food textures. I can't STAND squishy fat and chewy gristle, even a bit of it, in my food, so often it's simply easier to order something vegetarian at a restaurant than order the chicken chow mein and wonder, "Is it going to have that icky squishy cheap chicken that all the Asian restaurants use, with the fat and skin still on?"
Vegetarian cooking is also more ecologically sound, since you're eating low on the food chain. And since I garden, and can even keep chard and (with some care) lettuce going all year round, I have a supply of really, really fresh, sweet veggies of a quality that you can't get in the store. There's a world of difference between asparagus from the grocery section and asparagus fresh cut from your own garden. There are delicious varieties of vegetables and fruits that you can't buy at the store at all (I grow a variety of carrot that is so sweet and crisp that you can't just yank it out of the ground it or it will break off -- you have to dig it up. And I can't find salsify, also called oyster root, at the store at all). And how much more pleasant it is to walk outside a pluck fresh, soft sprigs of rosemary than to shake dry little needles out of a jar.
When I do use meat, I often prefer to use it IN things, as an ingredient or even a condiment rather than a large slab of boring plain meat. And that's another way for carnivores to taper off: find good "peasant food" dishes that use small amounts of meat, like Tuscan pasta dishes with white beans and rosemary in a wine sauce with slices of sausage. Before you know it, you can leave out the sausage and hardly notice. If you go for gourmet vegetarian cooking instead of the dreary "Drink your soy-molasses-brewer's yeast super drink and eat your tofu loaf because they're GOOD for you!" routine that characterized (rightly or wrongly) so much of the 70's health food movement, you'll soon find yourself thinking, "Broiled chicken breast? With mashed potatoes and peas? That's it? Booooring!"
