[JS][Packaging] npm package is bloated with seemingly unnecessary code/deps

Start by inspecting the published @apache-arrow/es5-cjs package contents and the Lerna package layout, including src and bin/arrow2csv.js. Measure which listed files and dependencies are required at runtime, then define package boundaries and verify that the published archives are smaller without breaking Node, browser, or TypeScript consumers.

Describe the enhancement requested

We're considering using Apache Arrow for a project, but it seems like the dependency is very large. For example, the @apache-arrow/es5-cjs package is 2.82MB compressed. It seems that the project was already split between target ES version and module loader for size efficiency, but without actually addressing the size problem.

From looking at the folder, I see the following components that could potentially be removed at a glance:

• All .ts files, as these are only needed in development when using TypeScript. (this includes definition files and the entire src folder)
• All .dom and .map files since these are only needed in the browser and not in Node.
• The bin/arrow2csv.js file as it seems to only be useful for testing.
• All @swc dependencies, as these are development dependencies.
• All @types dependencies, as those should be installed separately only when using TypeScript.
• The command-line-args and command-line-usage dependencies as they seem like development dependencies.
• The tslib dependency, which again is related to TypeScript and cannot be used by Node.
• The json-bignum dependency, as it doesn't seem to make sense if this project is actually an alternative to JSON to begin with.
• For the flatbuffers dependency, I'm not entirely sure, but it seems to support generating code from a schema, which may include all or some of the code needed to no longer need flatbuffers, although for this one, additional investigation would be needed.
• I'm sure a lot of other files are used to do things like managing schemas and could potentially be removed as well from the production package.

Deleting all the above (except flatbuffers as it's unclear if it's needed) just to see the difference results in the uncompressed package size going from 6.4MB to 1.3MB, and it's probably incomplete and could be reduced much further.

I don't know much about the project internals, so my above assumptions might be wrong, but I'd definitely like to open a discussion about the size of this package and how to make it smaller as it seems the current approach to split packages is not quite achieving its goal and it might make more sense to split the project to something closer to a monorepo.

For example, something like this:

@apache-arrow/cli
@apache-arrow/types or @types/apache-arrow
@apache-arrow/node (doesn't need to be split by module types as only the entry point needs to change)
@apache-arrow/dom-es2015 (or es5, etc)
etc

Or even more granular (since for example we only need the ability to encode and not decode):

@apache-arrow/encoder
@apache-arrow/decoder
@apache-arrow/stream-writer
@apache-arrow/stream-reader
etc

Since the project already relies on Lerna, it shouldn't be too much work to change what gets released as what package I think, but I'd like to hear thoughts from maintainers before opening a PR with such a large restructuring of the project.

Component(s)

JavaScript, Packaging