The point of my comment was that if the only issue here were my particular taste preferences than there wouldn't be an issue. I personally think seitan tastes like cardboard, but I wouldn't use that as a basis to argue against seitan, instead its that non-vegetarians tend to think of mock dishes as inferior to what they are use to eating and as a result think of vegetarianism as some sort of great sacrifice. That is, I think, unfortunate because traditional vegetarian food prepared with whole ingredients is just as delicious....but few people are being exposed to this sort of vegetarian food.
The other major difference was the use of refined rather than whole grains, but the use of refined grains is more common and I find that the routine consumption of refined grains and mock meats go hand to hand. But no matter how you substitute matters, if you replace mock meats and cheese for more nutritious alternatives is going to lower the nutritional value of the menu and at some point the menu starts to become nutritionally unbalanced. To some degree, as you mentioned before, people can offset the poor nutritional value of mock meat and cheese by including foods with very high nutritional value but that requires conscious effort and doesn't seem to be common practice. People that are concerned with the healthfulness of their diet tend to make healthful choices in general, where as routine consumption of mock meats/cheese tends to follow other less than wholesome dietary practices (e.g., consumption of rich deserts, consumption of refined grains, etc). But my second menu wasn't overtly bad, I think many people would think of it as being relatively healthy. A second issue is that mock meats tend to negative attributes above and beyond their low nutritional value, for example, most are very high in sodium (to hide the cardboard taste!) and many are high in refined fats.
I think we have a pretty good idea about what is required to stay healthy and if a vegetarian and vegan follows dietary recommendations it doesn't leave much room for mock cheese, mock meats, etc. I don't think there is much question on this front, I think the question is whether vegetarians and vegans can routinely eat mock meats/cheese and maintain a nutritionally adequate, even if unhealthy, diet. I think the answer to this is, in general, no and the high number of failed vegetarians and vegans is a testament to it. Many ex-vegetarians and vegans report a failure to thrive.