Eat your megetables!

[Erloas]

First to the question of "why soy" is because soy has been used for a long time, even as a protein source. Tofu has been around for 2000 years already, it was really easy to expand that into newer and different things.

With the buggers, they do burgers and hotdogs because they are easier and significantly less dependent on texture to taste right (or it is an easier texture to match at very least). I also think it has to do with how people eat them, very few people just eat a hamburger patty or hotdog on it's own, you've got bread, often pickles, mustard, catsup, and all sorts of other things, so it is really easy to miss small changes in the meat itself. But steak is ate pretty much on it's own, the taste and texture of the meat stands on it's own, it has nothing to hide in or mix with.
They are also lower end products, something you can get to the masses. They are staples of fast food and casual restaurants, family gatherings, and events of all sorts. The sort of places where having unusual food requirements tends to become more of a social issue.

Through I do wonder, where is it proven that vat-grown meat has different nutritional properties then a hunk of animal? I'm curious as to what the difference is.

Because the nutrients in meat (and to a lesser extend vegetables as well) is very much dependent on what the creature ate before you ate it. For instance free range beef is nutritionally significantly different than farm raised beef. Chicken that get a full range diet, like bugs, lizards, and all sorts of other things, rather than simple grains, have a lot more nutrients in their meat as well. The more different things an animal gets to eat the more places it can pick up nutrients that are then stored in it, and you get it from eating them. It is also true for vegetables, you can some types to grow really fast with a lot of water and sun, but they also tends to taste worse and aren't as good for you because they just didn't have the time and availability to pick up said nutrients. Granted it is easier, and pretty much required, to add some outside sources of nutrients to keep plants growing, the plants take in micro and macro nutrients from fertilizers (both natural and man made) and turn them into other compounds.

What that means though is that once they get to that point vat-grown meat could actually be much better for you because they could add all the nutrients into the vats for the meat to take up while it grows. Of course the issue is mostly economics, you could easily feed real animals a better mix of foods to make them more nutritious, but it would cost more, so they don't. So there is a good chance only high end "designer" vat-grown meat would have all the extras, and the mass-market stuff would just be the cheapest mix they can provide to get it to grow.