(Written as an "answer" rather than a "comment" but nevertheless all the below is just my own personal opinion.)

I had a similar reaction when I recently came across the "Growth vs Randomista Development" post, and I think that EA is probably making a mistake by not focusing more on the "medium-termist" cause area of economic growth interventions. I think there are several understandable reasons why this has happened:

Most importantly, I think economic growth interventions fall into a gap between longtermism and near-termism. People who want to know for certain that their money/efforts are helping people today at a guaranteed high level of effectiveness, can use Givewell top charities. Economic interventions work less well because "lobbying" approaches are much more indirect and ascribing causality is hard, plus lobbying for political change to economic policies (as contrasted with existing lobbying projects for public health improvements, or climate mitigation, or animal welfare fixes) tend to be more controversial and not universally acknowledged as "good".

People who accept longtermist arguments (that we should just aim for highest-expected-value, even amid crazy high uncertainty and even if that causes us to pour everything into wild X-risk-prevention moonshots) mostly seem to jump all the way into standard longtermism.

As a pretty committed longtermist myself, I certainly see where these people are coming from. But all the arguments for why even longtermists should think it's good to have a neartermist component to EA (building up a legible reputation of altruism, getting practice actually accomplishing big things and building strong organizations, getting feedback loops, making sure that the movement is genuinely helping people rather than becoming too meta, etc) also apply to medium-term interventions. For all those reasons, I would like to see economic growth interventions join EA as another core pillar of the movement alongside animal welfare, x-risk reduction, and global heath.

Besides the idea that economic growth interventions have fallen into a medium-termist "gap", there are some other factors that also contribute:

• It's intrinsically more political, which makes it sit a bit uneasily with EA's current stance of trying to avoid partisan political polarization. IMO, "progress studies" has a good approach showing how economic growth advocacy can be done in a relatively less-polarized way. Also, an EA "economic growth interventions" wing would probably start with a focus on developing countries rather than US policy; the cultural distance involved would make this less a magnet for controversy than eg a full endorsement of the political platform advocated by r/neoliberal. (Also, it's worth noting that Openphil has for years had a small "US policy" division advocating for YIMBY, increased immigration, reduced mass incarceration, and better monetary policy, without attracting too much controversy.)

• It's arguably less neglected: there are more existing institutions in the space (like the IMF), plus there's the fact that profit-seeking actors are motivated to increase economic growth in many ways. (Nations desire economic growth in order to compete against each other; individual entrepreneurs naturally help spread new technologies and business models; one could hope to run a charter city as a highly profitable venture-capital project in a way that could never be true of most EA health interventions.) But nevertheless I think an EA mindset could bring lots of value to the table, just like EAs bring a lot to the global health field despite the existence of UN agencies, international aid budgets, etc.

• EA tries to be cause-neutral and open minded, and it lives up to these goals to a remarkable degree, but there is naturally still plenty of organizational inertia, so it takes time to turn the ship even to the extent that people all agree with the idea of supporting economic growth interventions more. Personally I think some good early steps in this direction would be to support and engage more with progress-studies-affiliated organizations like Charter Cities Institute. Then over time we could seek to incubate our own new charities in this space, along the lines of existing developing-world lobbying projects like Lead Elimination Project and Shrimp Welfare Project.

As I understand it, no there has been no additional effort into researching economic growth, nor has anyone responded to either of the posts you mention.

There has been some new research into policy change air pollution in Asia.  

1. As Jackson points out, those willing to go the 'high uncertainty/high upside' route tend to favor far future or animal welfare causes. Even if we think these folks should consider more medium-term causes, comparing cost-effectiveness to GiveWell top charities may be inapposite.
2. It seems like there is support for hits-based policy interventions in general, and Open Phil has funded at least some of this.
3. The case for growth was based on historical success of pro-growth policy. Not only is this now less neglected, but much of the low-hanging fruit has been taken.

I'll add one small comment regarding this. I think that the claim that "resources devoted toward economic development tends to do more good than resources toward small-scale health interventions" makes sense. On three different occasions when I've mentioned randomized control trials as a great way for creating new knowledge, I've had EAs refer me to this article as if this article was a critique of RCTs. Thus, I suspect that multiple people have misinterpreted the aim of the article, and are mentally categorizing it as "a critique of RCTs" rather than as "a critique of small scale interventions as less effective than economic growth."