What I have heard before is: - more resource-efficient and green since livestock farming requires a lot of feed and has a higher carbon footprint than all vehicles combined, and - that it's less cruel than raising animals to be slaughtered.
In terms of economics, a cheaper meat substitute would just mean a cheaper source of protein for people, comparable to eating vegetables.
As a side note, does anyone know why Paul Graham has been talking about economic inequality recently? Is it just politics season and that this is a debate issue?
Back in January of 2016, in the aftermath of the occupy movement and the height of the US presidential campaign, he penned this essay as a sort of "defense" of inequality:
http://www.paulgraham.com/ineq.html
We're ramping back up to another presidential election, the concerns about inequality have only gotten greater, and for the first time, mass transformation of dietary habits via technology as a way to combat climate change has gone from a niche to a national topic.
'Meat substitutes' are going to be grown in fairly sophisticated labs and sourced from artificially reproduced or otherwise obtained cells. And it's not going to taste like e.g. chicken once the cells are grown. The taste you know from various meats is a product of that animal's physiology and diet. The meat will also not have the same texture. So once you grow your cells in a lab you then need to artificially flavor them and then artificially generate a meat-like texture. The upfront costs for this will all not only be very expensive but there will also be a minefield of intellectual property, patent, and other such barriers all throughout the field. This is why the first artificial meat companies are working on is hamburger -- you can simply grind up the cells and then dump in lots of flavoring.
I expect we'll see the same thing happen to meat that happened with genetically engineered plants. The entire industry will be rapidly monopolized. And our new 'Meatsanto' will undoubtedly lobby the government for favorable treatment which at the minimum will include them being able to label these artificially flavored and textured cells as simply 'chicken'. Add in artificial undercutting of prices and other incentives and you'll see Meatsanto gain more and more marketshare, perhaps including licensing their technology to ranchers now put out of business. And it's at that point, once the monopoly and dependence is established, that they begin to squeeze their new monopoly and start printing billions.
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I think there's a pretty simple rule of thumb. Centralization leads to wealth inequality, decentralization leads to more equitable wealth distribution. When you add barriers to entry, you create centralization. As an example of this consider shoes. At one time shoes were an industry that used to support countless thousands (millions?) of cobblers, apprentices, and their local market interrelations. It's now been replaced by a small handful of multinational corporations that produce billions of shoes worldwide at immense profit margins. Of course in exchange shoes are undoubtedly now higher quality than they've ever been, and you can pick up a reasonable pair of shoes for a few hours of minimum wage, but I do not think more affordable shoes positively affects wealth inequality as much as removing immense number of jobs and redirecting all proceeds to a handful of companies does to negatively affect it.