Just a few remarks: VLC-Unity plugin is fully open source, and anyone skilled enough can build it themself.
We've tried for months to discuss with Unity and it was a nightmare. We've had discussions for years with Apple AppStore, Google Play store, and Windows Stores (including Windows Mobile + UWP). It's always challenging, but Unity was a headache an order of magnitude bigger: no answers, 3 different answers contradicting each other, and plain bad faith.
De facto, they use LGPL and open source to build their platform, but we're not allowed to have open source on the store? Not even LGPL with a layer of a different license? Why us? Why not the other people doing it?
Very frustrating.
So, yes, because some people need to buy support or licenses, even if everything is open source (don't want to build themselves, purchase department that needs a support contract, etc...), they need to have a small store. This is different from what we see usually, but there is a need, so this is a small store for that.
For most of HN users, you should just build it yourself. You should be skilled enough for that :)