To me one of the more compelling reasons to develop substitutes that closely resemble animal-produced originals (chemically, not just superficially) is the stag

To me one of the more compelling reasons to develop substitutes that closely resemble animal-produced originals (chemically, not just superficially) is the staggeringly huge number of recipes that depend on animal products. There are substitutes that work as a technicality right now, but it's usually trivial to tell the difference between a recipe using original ingredients vs. a recipe that's been "veganized" (most often, the result is more crumbly, less rich, has wrong texture, etc). Innovation in vegan food is a good thing that should be encouraged but it needn't come at the cost of large chunks of cultural heritage in the form of food. Vegan substitutes that are close analogues of animal-produced originals lets us have the best of both worlds.