Since it wasn't clear when WRI would get to this or even if they would do it well, I tried to roll my own version of a public repository. You can find it here

I talked about it some here and here

An exciting development that I had entirely missed. Per this Twitch stream

the first step is to make a documentable version of the paclet system

So as of Dec. 13 this was something of a priority.

Hopefully that means it will be available by Mathematica v22.

I understand where you're coming from. Safety is a concern with things like these. On the other hand without some form of centralized repository there's no way for the Mathematica developer community to thrive and without that I'd argue Mathematica will continue to lose to things like Jupyter. E.g. this bad omen of the future:

or the recent popular Atlantic article.

As for paclet servers I'm running one right now for free in Wolfram's cloud and I have to say I'm generally pretty happy except for one or two issues.

Alas this method suffers from the fact that PackageData.net is merely a collection of links. It does not make use of the PacletManager system that Mathematica has built-in. It is better than MathSource though.

To my mind anything that doesn’t effectively link into the PacletManager isn’t sufficient. There’s been ample discussion of this over on the StackExchange in the PackageData.net chat room.

I am more than well-aware of Begin and BeginPackage: https://github.com/b3m2a1. I even know about paclets.

The point is that these are not centralized in a browsable package repository the way they should have been. The paclet repository (presumably it will live at http://resources.wolframcloud.com/PacletRepository by analogy to the DataRepository, NeuralNetRepository, and the seemingly soon to be coming FunctionRepository).

In terms of what does exist, there's PackageData.net but it doesn't have a link-in to the PacletManager and in any case most people there don't make paclets.

In all honestly WRI should have done this a decade ago, but as long as it comes soon I'm not one to grouse too much.

The primary issue with this is that MathSource is a suboptimal distribution platform. At that point it’s better to just use GitHub as that’s the modern way to distribute source code. You can set up good documentation in GitHub. It just takes effort.

I'd upvote this 100 times if I could. Thanks for this, Szabolcs. I feel like this has much more impact coming from someone with more respect in the community.

And just so it doesn't get lost–it seems like something like this is coming–the question is simply when it will come and what it will look like. With luck it will be as at least half as good as as the PyPI.