Shopify has an insanely slow theme development cycle. Here are some simple things that could quickly fix that.
1. A localhost server. Developers should be able to see code updates in real time without deploying every minor change. I should be able to request the `.json` version of a page locally on a password protected store. Even if you don't offer me a way to serve liquid locally, offering a dev json api would save a ton of time. This is as simple as a second API stage. If you offered this, I could run my own react/vue/express server locally and then inject my react code into the Shopify theme in production, which would speed up the dev cycle and decrease the number of deploys substantially.
2. A real development environment for private themes. I should have a separate dev database and json api to test things out without creating a real product, collection, etc. Since you're using ruby on rails under the hood, this should be very simple.
3. A real interface for creating our own API endpoints. Right now, it seems like the only way to customize the Shopify API is by manually writing out json and an alternate template and using the `json` filter for a Shopify object. Why isn't there a liquid method for me to construct my own key/value objects and arrays? That's a primitive in almost every programming language. It makes no sense to restrict developers this way.
It seems like theme development is set up to intentionally restrict developers, in order to keep all code updates within the Shopify ecosystem. But if that makes it difficult to develop themes, then what's the point? Why not do the bare minimum to make our lives easier?