A big technical reason especially specific to using Typescript: not transpiling to CJS speeds up your Typescript builds. It also opens up more options when Typ

A big technical reason especially specific to using Typescript: not transpiling to CJS speeds up your Typescript builds. It also opens up more options when Typescript is just "type stripped" rather than transpiled to an incompatible module syntax. You probably still want a full Typescript compile at CI time to get robust typechecking, and you'll have the Typescript LSP doing its thing in your IDE still, but you can use type-stripping tools like esbuild for very fast type stripping in some portions of your inner dev loop. The static analysis that ESM supports is handy because it opens up technical benefits like Tree Shaking. Your apps might run on SSDs, you probably don't have a lot of reasons to bundle them, you likely aren't worried about on disk size, you might not be worried about bundle publish size to npm, and so you might not think Tree Shaking applies to you, but V8 under the hood of Node is still going to do Tree Shaking of memory and garbage collection for you with ESM in ways that it simply cannot with CJS. I've seen some real memory performance gains in Node apps just switching from CJS to ESM already, and V8's ESM optimizations only seem to get better as more ESM is deployed in the wild. There are more, smaller technical benefits, but "type stripping not transpiling" and "in memory tree shaking" are strong ones that are easy to overlook.